Invalid postback or callback argument Event validation is enabled using pages enableEventValidation true

Question

I am getting the following error when I post back a page from the client-side  I have JavaScript code that modifies an asp ListBox on the client side   How do we fix this   Error details below   Server Error in   XXX  Application   -------------------------------------------------------------------------------- Invalid postback or callback argument   Event validation is enabled using  lt pages enableEventValidation  true   gt  in configuration or  lt    Page EnableEventValidation  true    gt  in a page   For security purposes  this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them   If the data is valid and expected  use the ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation  Description  An unhandled exception occurred during the execution of the current web request  Please review the stack trace for more information about the error and where it originated in the code   Exception Details  System ArgumentException  Invalid postback or callback argument   Event validation is enabled using  lt pages enableEventValidation  true   gt  in configuration or  lt    Page EnableEventValidation  true    gt  in a page   For security purposes  this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them   If the data is valid and expected  use the ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation   Source Error   An unhandled exception was generated during the execution of the current web request  Information regarding the origin and location of the exception can be identified using the exception stack trace below   Stack Trace    ArgumentException  Invalid postback or callback argument   Event validation is enabled using  lt pages enableEventValidation  true   gt  in configuration or  lt    Page EnableEventValidation  true    gt  in a page   For security purposes  this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them   If the data is valid and expected  use the ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation      System Web UI ClientScriptManager ValidateEvent String uniqueId  String argument   2132728    System Web UI Control ValidateEvent String uniqueID  String eventArgument   108    System Web UI WebControls ListBox LoadPostData String postDataKey  NameValueCollection postCollection   274    System Web UI WebControls ListBox System Web UI IPostBackDataHandler LoadPostData String postDataKey  NameValueCollection postCollection   11    System Web UI Page ProcessPostData NameValueCollection postData  Boolean fBeforeLoad   353    System Web UI Page ProcessRequestMain Boolean includeStagesBeforeAsyncPoint  Boolean includeStagesAfterAsyncPoint   1194  -------------------------------------------------------------------------------- Version Information  Microsoft  NET Framework Version 2 0 50727 1433  ASP NET Version 2 0 50727 1433

User · Answer

If you know up front the data that could be populated, you can use the ClientScriptManager to resolve this issue. I had this issue when dynamically populating a drop down box using javascript on a previous user selection.

Here is some example code for overriding the render method (in VB and C#) and declaring a potential value for the dropdownlist ddCar.

In VB:

Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)

    Dim ClientScript As ClientScriptManager = Page.ClientScript

    ClientScript.RegisterForEventValidation("ddCar", "Mercedes")

    MyBase.Render(writer)
End Sub

or a slight variation in C# could be:

protected override void Render(HtmlTextWriter writer)
{
    Page.ClientScript.RegisterForEventValidation("ddCar", "Mercedes");
    base.Render(writer);
}

For newbies: This should go in the code behind file (.vb or .cs) or if used in the aspx file you can wrap in <script> tags.

User · Answer

I had the same problem with a Repeater because I had a web-page with a Repeater control in a web-site which had EnableEventValidation switched on  It wasn t good  I was getting invalid postback related exceptions   What worked for me was to set EnableViewState  false  for the Repeater  The advantages are that it is simpler to use  as simple as switching event validation off for the web-site or web-page  but the scope is a lot less than switching event validation off for either

User · Answer

Do you have codes in you Page Load events  if yes  then perhaps by adding the following will help   if   Page IsPostBack      do something     This error is thrown when you click on your command and the Page load is being ran again  in a normal life cycle will be Page Load -  Click on Command -  Page Load  again  -  Process ItemCommand Event

User · Answer

If you fill the DropdownList through client side script then clear the list before submit the form back to server  then ASP NET will not complain and the security will be still on   And to get the data selected from the DDL  you can attach an  OnChange  event to the DDL to collect the value in a hidden Input or in a textbox with Style  display  none

User · Answer

As Nick B said and that worked for me you have to remove line breaks in some cases  Take a look at the code   -Wrong way    lt asp DropDownList ID  DropDownList1  runat  server  gt       lt asp ListItem Selected  True  gt              Item 1 lt  asp ListItem gt       lt asp ListItem gt              Item 2 lt  asp ListItem gt       lt asp ListItem gt              Item 3 lt  asp ListItem gt   lt  asp DropDownList gt    -Right way    lt asp DropDownList ID  DropDownList1  runat  server  gt       lt asp ListItem Selected  True  gt Item 1 lt  asp ListItem gt       lt asp ListItem gt Item 2 lt  asp ListItem gt       lt asp ListItem gt Item 3 lt  asp ListItem gt   lt  asp DropDownList gt    It only ocurred for me in IE10

User · Answer

This was the reason why I was getting it   I had an ASP ListBox  Initially it was hidden  At client side I would populate it via AJAX with options  The user chose one option  Then when clicking the Submit button  the Server would get all funny about the ListBox  since it did not remember it having any options   So what I did is to make sure I clear all the list options before submitting the form back to the server  That way the server did not complain since the list went to the client empty and it came back empty   Sorted

User · Answer

I implemented a nested grid view and i faced the same problem  I have used LinkButton instead of image button like this   before i had a column like this    lt asp TemplateField ItemStyle-Width  9  gt     lt ItemTemplate gt    lt asp ImageButton ID  ImgBtn  ImageUrl  Include images gridplus gif  CommandName  Expand                          runat  server    gt     lt  ItemTemplate gt   lt  asp TemplateField gt    I have replaced like this    lt asp TemplateField gt   lt ItemTemplate gt        lt asp LinkButton  CommandName  Expand  ID  lnkBtn   runat  server   gt  lt asp Image  ID  Img   runat  server  ImageUrl    Images app plus gif    gt  lt  asp LinkButton gt         lt  ItemTemplate gt   lt  asp TemplateField gt

User · Answer

Ajax UpdatePanel makes it  and I think it s the easiest way  ignoring the Ajax postback overhead

User · Answer

The problem is that ASP NET does not get to know about this extra or removed listitem  You got an number of options  listed below     Disable eventvalidation  bad idea  because you lose a little of security that come with very little cost   Use ASP NET Ajax UpdatePanel   Put the listbox in the Updatepanel and trigger a update  if you add or remove listbox  This way viewstate and related fields get updates and eventvalidation will pass   Forget client-side and use the classic postback and add or remove the listitems server-side    I hope this helps

User · Answer

If you know up front the data that could be populated, you can use the ClientScriptManager to resolve this issue. I had this issue when dynamically populating a drop down box using javascript on a previous user selection.

Here is some example code for overriding the render method (in VB and C#) and declaring a potential value for the dropdownlist ddCar.

In VB:

Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)

    Dim ClientScript As ClientScriptManager = Page.ClientScript

    ClientScript.RegisterForEventValidation("ddCar", "Mercedes")

    MyBase.Render(writer)
End Sub

or a slight variation in C# could be:

protected override void Render(HtmlTextWriter writer)
{
    Page.ClientScript.RegisterForEventValidation("ddCar", "Mercedes");
    base.Render(writer);
}

For newbies: This should go in the code behind file (.vb or .cs) or if used in the aspx file you can wrap in <script> tags.

User · Answer

If you fill the DropdownList through client side script then clear the list before submit the form back to server  then ASP NET will not complain and the security will be still on   And to get the data selected from the DDL  you can attach an  OnChange  event to the DDL to collect the value in a hidden Input or in a textbox with Style  display  none

User · Answer

I know that this is a super-old post   Assuming that you are calling into your application  here is an idea that has worked for me    Implement the ICallbackEventHandler on your page Call ClientScriptManager GetCallbackEventReference to call your server side code As the error message states  you could then call ClientScriptManager RegisterForEventValidation   If you don t need total control  you could use an update panel which would do this for you

User · Answer

Ajax UpdatePanel makes it  and I think it s the easiest way  ignoring the Ajax postback overhead

User · Answer

We ran into this same issue when we were converting our regular ASPX pages to Content pages    The page with this issue had a  lt  form gt  tag within one of the Content sections  thus two form end tags were rendered at run time which caused this issue  Removing the extra form end tag from the page resolved this issue

User · Answer

For us the problem was happening randomly only in the production environment  The RegisterForEventValidation did nothing for us   Finally  we figured out that the web farm in which the asp net app was running  two IIS servers had different  net versions installed  So it appears they had different rules for encrypting the asp net validation hash  Updating them solved most of the problem    Also  we configured the machineKey compatibilityMode   the same in both servers   httpRuntime targetFramework   ValidationSettings UnobtrusiveValidationMode  pages renderAllHiddenFieldsAtTopOfForm  in the web config of both servers   We used this site to generate the key https   www allkeysgenerator com Random ASP-Net-MachineKey-Generator aspx  We spent a lot of time solving this  I hope this helps somebody    lt appSettings gt      lt add key  ValidationSettings UnobtrusiveValidationMode  value  None    gt       lt  appSettings gt   lt system web gt      lt machineKey compatibilityMode  Framework45  decryptionKey  somekey  validationKey  otherkey  validation  SHA1  decryption  AES   gt      lt pages       controlRenderingCompatibilityVersion  4 0  enableEventValidation  true  renderAllHiddenFieldsAtTopOfForm  true    gt      lt httpRuntime       requestValidationMode  2 0  targetFramework  4 5    gt       lt  system web gt

User · Answer

The problem is that ASP NET does not get to know about this extra or removed listitem  You got an number of options  listed below     Disable eventvalidation  bad idea  because you lose a little of security that come with very little cost   Use ASP NET Ajax UpdatePanel   Put the listbox in the Updatepanel and trigger a update  if you add or remove listbox  This way viewstate and related fields get updates and eventvalidation will pass   Forget client-side and use the classic postback and add or remove the listitems server-side    I hope this helps

User · Answer

If you are using Ajax update panel  Add  lt Triggers gt  tag and inside it trigger the Button or control causing the postBack using  lt asp PostBackTrigger      gt

User · Answer

You are really going to want to do 2 or 3  don t disable event validation   There are two main problems with adding items to an asp listbox client side    The first is that it interferes with event validation   What came back to the server is not what it sent down  The second is that even if you disable event validation  when your page gets posted back the items in the listbox will be rebuilt from the viewstate  so any changes you made on the client are lost   The reason for this is that a asp net does not expect the contents of a listbox to be modified on the client  it only expects a selection to be made  so it discards any changes you might have made    The best option is most likely to use an update panel as has been recommended   Another option  if you really need to do this client side  is to use a plain old  lt select gt  instead of an  lt asp ListBox gt   and to keep your list of items in a hidden field   When the page renders on the client you can populate it from a split of your text field contents     Then  when you are ready to post it  you repopulate the hidden field s contents from your modified  lt select gt    Then  of course  you have to split that again on the server and do something with your items  since your select is empty now that it s back on the server   All in all it s a pretty cumbersome solution that I would not really recommend  but if you really have to do client-side modifications of a listBox  it does work   I would really recommend you look into an updatePanel before going this route  however

User · Answer

I had a similar issue  but I was not using ASP Net 1 1 nor updating a control via javascript  My problem only happened on Firefox and not on IE       I added options to a DropDownList on the PreRender event like this   DropDownList DD    DropDownList F FindControl  DDlista    HiddenField HF    HiddenField F FindControl  HFlista    string   opcoes   HF value Split   n    foreach  string opcao in opcoes  DD Items Add opcao     My  HF   hiddenfield  had the options separated by the newline  like this   HF value    option 1 n roption 2 n roption 3     The problem was that the HTML page was broken  I mean had newlines  on the options of the  select  that represented the DropDown   So I resolved my my problem adding one line   DropDownList DD    DropDownList F FindControl  DDlista    HiddenField HF    HiddenField F FindControl  HFlista    string dados   HF Value Replace   r        string   opcoes   dados Split   n    foreach  string opcao in opcoes  DD Items Add opcao     Hope this help someone

User · Answer

I had an experience with DataGrid  One of it s columns was  Select  button  When I was clicking  Select  button of any row I had received this error message       Invalid postback or callback argument   Event validation is enabled using  in configuration or        lt    Page EnableEventValidation  true     in a page   For security purposes  this feature verifies that arguments to postback or       callback events originate from the server control that originally rendered them   If the data is valid and expected  use the       ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation     I changed several codes  and finally I succeeded  My experience route   1  I changed page attribute to EnableEventValidation  false   But it didn t work    not only is this dangerous    for security reason  my event handler wasn t called  void Grid SelectedIndexChanged object sender  EventArgs e   2  I implemented ClientScript RegisterForEventValidation in Render method  But it didn t work   protected override void Render HtmlTextWriter writer        foreach  DataGridItem item in this Grid Items                Page ClientScript RegisterForEventValidation item UniqueID           foreach  TableCell cell in  item as TableRow  Cells                        Page ClientScript RegisterForEventValidation cell UniqueID               foreach  System Web UI Control control in cell Controls                                if  control is Button                      Page ClientScript RegisterForEventValidation control UniqueID                                     3  I changed my button type in grid column from PushButton to LinkButton  It worked    ButtonType  LinkButton    I think if you can change your button to other controls like  LinkButton  in other cases  it would work properly

User · Answer

I was using datalist and I was getting the same error for my push button  I just use IsPostBack to check and fill my controls and the problem is solved  Great

User · Answer

The following example shows how to test the value of the IsPostBack property when the page is loaded in order to determine whether the page is being rendered for the first time or is responding to a postback  If the page is being rendered for the first time  the code calls the Page Validate method  The page markup  not shown  contains RequiredFieldValidator controls that display asterisks if no entry is made for a required input field  Calling Page Validate causes the asterisks to be displayed immediately when the page is rendered  instead of waiting until the user clicks the Submit button  After a postback  you do not have to call Page Validate  because that method is called as part of the Page life cycle       private void Page Load                 if   IsPostBack

User · Answer

When I added the id on ItemDataBound then it did not give me the error  but it was not giving me the command name  It was returning command name empty  Then I added command name as well while ItemDataBound  Then it resolved the same problem  Thanks Nilesh  great suggestion  It Worked

User · Answer

Four minutes ago I received the same error  Then I have researched during one half hour like you  In all forums they are generally saying  add page enableEvent   false or true   Any solution proposed didn t resolved my problems until I found it  The problem is unfortunately an ASP NET button  I removed it two seconds ago  I tried to replace with  imagebutton   but it was also unacceptable  because it gave the same error    Finally I have replaced with LinkButton  it seems to be working

User · Answer

I implemented a nested grid view and i faced the same problem  I have used LinkButton instead of image button like this   before i had a column like this    lt asp TemplateField ItemStyle-Width  9  gt     lt ItemTemplate gt    lt asp ImageButton ID  ImgBtn  ImageUrl  Include images gridplus gif  CommandName  Expand                          runat  server    gt     lt  ItemTemplate gt   lt  asp TemplateField gt    I have replaced like this    lt asp TemplateField gt   lt ItemTemplate gt        lt asp LinkButton  CommandName  Expand  ID  lnkBtn   runat  server   gt  lt asp Image  ID  Img   runat  server  ImageUrl    Images app plus gif    gt  lt  asp LinkButton gt         lt  ItemTemplate gt   lt  asp TemplateField gt

User · Answer

None of the above worked for me  After more digging I realized I had overlooked 2 forms applied on the page which was causing the issue    lt body gt   lt form id  form1  runat  server  gt   lt div gt           lt form action     method  post  class  form  role  form  gt           lt div gt                       lt asp Button ID  submitButton  runat  server           lt  div gt   lt  div gt   lt  body gt    Be aware that recently ASP NET has started considering iframes within a form tag which contains a form tag in the iframe document itself a nested frame  I had to move the iframe out of the form tag to avoid this error

User · Answer

Do you have codes in you Page Load events  if yes  then perhaps by adding the following will help   if   Page IsPostBack      do something     This error is thrown when you click on your command and the Page load is being ran again  in a normal life cycle will be Page Load -  Click on Command -  Page Load  again  -  Process ItemCommand Event

User · Answer

I had an experience with DataGrid  One of it s columns was  Select  button  When I was clicking  Select  button of any row I had received this error message       Invalid postback or callback argument   Event validation is enabled using  in configuration or        lt    Page EnableEventValidation  true     in a page   For security purposes  this feature verifies that arguments to postback or       callback events originate from the server control that originally rendered them   If the data is valid and expected  use the       ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation     I changed several codes  and finally I succeeded  My experience route   1  I changed page attribute to EnableEventValidation  false   But it didn t work    not only is this dangerous    for security reason  my event handler wasn t called  void Grid SelectedIndexChanged object sender  EventArgs e   2  I implemented ClientScript RegisterForEventValidation in Render method  But it didn t work   protected override void Render HtmlTextWriter writer        foreach  DataGridItem item in this Grid Items                Page ClientScript RegisterForEventValidation item UniqueID           foreach  TableCell cell in  item as TableRow  Cells                        Page ClientScript RegisterForEventValidation cell UniqueID               foreach  System Web UI Control control in cell Controls                                if  control is Button                      Page ClientScript RegisterForEventValidation control UniqueID                                     3  I changed my button type in grid column from PushButton to LinkButton  It worked    ButtonType  LinkButton    I think if you can change your button to other controls like  LinkButton  in other cases  it would work properly

User · Answer

After having this problem on remote servers  production  test  qa  staging  etc   but not on local development workstations  I found that the Application Pool was configured with a RequestLimit other than 0    This caused the app pool to give up and reply with the exception noted in the question

User · Answer

None of the above worked for me  After more digging I realized I had overlooked 2 forms applied on the page which was causing the issue    lt body gt   lt form id  form1  runat  server  gt   lt div gt           lt form action     method  post  class  form  role  form  gt           lt div gt                       lt asp Button ID  submitButton  runat  server           lt  div gt   lt  div gt   lt  body gt    Be aware that recently ASP NET has started considering iframes within a form tag which contains a form tag in the iframe document itself a nested frame  I had to move the iframe out of the form tag to avoid this error

User · Answer

FYI I had the same issue with that error message and it was that I had 2 form tags on the same page  There was one in the Master page and one in the page itself  Soon as I removed the second form tag pair the problem went away

User · Answer

The problem is that ASP NET does not get to know about this extra or removed listitem  You got an number of options  listed below     Disable eventvalidation  bad idea  because you lose a little of security that come with very little cost   Use ASP NET Ajax UpdatePanel   Put the listbox in the Updatepanel and trigger a update  if you add or remove listbox  This way viewstate and related fields get updates and eventvalidation will pass   Forget client-side and use the classic postback and add or remove the listitems server-side    I hope this helps

User · Answer

You are really going to want to do 2 or 3  don t disable event validation   There are two main problems with adding items to an asp listbox client side    The first is that it interferes with event validation   What came back to the server is not what it sent down  The second is that even if you disable event validation  when your page gets posted back the items in the listbox will be rebuilt from the viewstate  so any changes you made on the client are lost   The reason for this is that a asp net does not expect the contents of a listbox to be modified on the client  it only expects a selection to be made  so it discards any changes you might have made    The best option is most likely to use an update panel as has been recommended   Another option  if you really need to do this client side  is to use a plain old  lt select gt  instead of an  lt asp ListBox gt   and to keep your list of items in a hidden field   When the page renders on the client you can populate it from a split of your text field contents     Then  when you are ready to post it  you repopulate the hidden field s contents from your modified  lt select gt    Then  of course  you have to split that again on the server and do something with your items  since your select is empty now that it s back on the server   All in all it s a pretty cumbersome solution that I would not really recommend  but if you really have to do client-side modifications of a listBox  it does work   I would really recommend you look into an updatePanel before going this route  however

User · Answer

When I added the id on ItemDataBound then it did not give me the error  but it was not giving me the command name  It was returning command name empty  Then I added command name as well while ItemDataBound  Then it resolved the same problem  Thanks Nilesh  great suggestion  It Worked

User · Answer

I had the same problem  two list boxes and two buttons   The data in the list boxes was being loaded from a database and you could move items between boxes by clicking the buttons   I was getting an invalid postback   turns out that it was the data had carriage return line feeds in it which you cannot see when displayed in the list box   worked fine in every browser except IE 10 and IE 11   Remove the carriage return line feeds and all works fine

User · Answer

I worked around this exact error by not adding the ListBox to a parent Page Control Controls collection  Because I really didn t need any server-side functionality out of it  I just wanted to use it to output the HTML for a custom server control  which I did in the OnRender event handler myself  I hoped that using the control would save me from writing to the response my own html   This solution probably won t work for most  but it keeps ASP NET from performing the ValidateEvent against the control  because the control doesn t retain in memory between postbacks   Also  my error was specifically caused by the selected list item being an item that wasn t in the listbox the previous postback  Incase that helps anyone

User · Answer

A simple solution for this problem is to use the IsPostBack check on your page load  That will solve this problem

User · Answer

if you change UseSubmitBehavior  True   to  UseSubmitBehavior  False  your problem will be solved   lt asp Button ID  BtnDis  runat  server  CommandName  BtnDis  CommandArgument   lt   Eval  Id    gt   Text  Discription  CausesValidation  True  UseSubmitBehavior  False    gt

User · Answer

For us the problem was happening randomly only in the production environment  The RegisterForEventValidation did nothing for us   Finally  we figured out that the web farm in which the asp net app was running  two IIS servers had different  net versions installed  So it appears they had different rules for encrypting the asp net validation hash  Updating them solved most of the problem    Also  we configured the machineKey compatibilityMode   the same in both servers   httpRuntime targetFramework   ValidationSettings UnobtrusiveValidationMode  pages renderAllHiddenFieldsAtTopOfForm  in the web config of both servers   We used this site to generate the key https   www allkeysgenerator com Random ASP-Net-MachineKey-Generator aspx  We spent a lot of time solving this  I hope this helps somebody    lt appSettings gt      lt add key  ValidationSettings UnobtrusiveValidationMode  value  None    gt       lt  appSettings gt   lt system web gt      lt machineKey compatibilityMode  Framework45  decryptionKey  somekey  validationKey  otherkey  validation  SHA1  decryption  AES   gt      lt pages       controlRenderingCompatibilityVersion  4 0  enableEventValidation  true  renderAllHiddenFieldsAtTopOfForm  true    gt      lt httpRuntime       requestValidationMode  2 0  targetFramework  4 5    gt       lt  system web gt

User · Answer

One other way not mentioned here is to subclass ListBox  Ie    public class ListBoxNoEventValidation   ListBox        ClientEventValidation keys off the attribute System Web UI SupportsEventValidation  if you subclass it  unless you explicitly add it back in  it will never call the validation routine   That works with any control  and is the only way I ve found to  disable  it on a control by control basis  Ie  not page level

User · Answer

1  EnableEventValidation  false                    It does not work for me    2  ClientScript RegisterForEventValidation    It does not work for me   Solution 1   Change Button ImageButton to LinkButton in GridView  It works   But I like ImageButton   Research  Button ImageButton and LinkButton use different methods to postback  Original article   http   geekswithblogs net mahesh archive 2006 06 27 83264 aspx  Solution 2   In OnInit     enter the code something like this to set unique ID for Button ImageButton    protected override void OnInit EventArgs e      foreach  GridViewRow grdRw in gvEvent Rows       Button deleteButton    Button grdRw Cells 2  Controls 1      deleteButton ID    btnDelete     grdRw RowIndex ToString                       Original Article    http   www c-sharpcorner com Forums Thread 35301

User · Answer

I ve had the same problem  what I did   Just added a condition if  IsPostBack  and it works fine

User · Answer

You are really going to want to do 2 or 3  don t disable event validation   There are two main problems with adding items to an asp listbox client side    The first is that it interferes with event validation   What came back to the server is not what it sent down  The second is that even if you disable event validation  when your page gets posted back the items in the listbox will be rebuilt from the viewstate  so any changes you made on the client are lost   The reason for this is that a asp net does not expect the contents of a listbox to be modified on the client  it only expects a selection to be made  so it discards any changes you might have made    The best option is most likely to use an update panel as has been recommended   Another option  if you really need to do this client side  is to use a plain old  lt select gt  instead of an  lt asp ListBox gt   and to keep your list of items in a hidden field   When the page renders on the client you can populate it from a split of your text field contents     Then  when you are ready to post it  you repopulate the hidden field s contents from your modified  lt select gt    Then  of course  you have to split that again on the server and do something with your items  since your select is empty now that it s back on the server   All in all it s a pretty cumbersome solution that I would not really recommend  but if you really have to do client-side modifications of a listBox  it does work   I would really recommend you look into an updatePanel before going this route  however

User · Answer

I had the same problem with a Repeater because I had a web-page with a Repeater control in a web-site which had EnableEventValidation switched on  It wasn t good  I was getting invalid postback related exceptions   What worked for me was to set EnableViewState  false  for the Repeater  The advantages are that it is simpler to use  as simple as switching event validation off for the web-site or web-page  but the scope is a lot less than switching event validation off for either

User · Answer

I ve had the same problem  what I did   Just added a condition if  IsPostBack  and it works fine

User · Answer

After having this problem on remote servers  production  test  qa  staging  etc   but not on local development workstations  I found that the Application Pool was configured with a RequestLimit other than 0    This caused the app pool to give up and reply with the exception noted in the question

User · Answer

You are really going to want to do 2 or 3  don t disable event validation   There are two main problems with adding items to an asp listbox client side    The first is that it interferes with event validation   What came back to the server is not what it sent down  The second is that even if you disable event validation  when your page gets posted back the items in the listbox will be rebuilt from the viewstate  so any changes you made on the client are lost   The reason for this is that a asp net does not expect the contents of a listbox to be modified on the client  it only expects a selection to be made  so it discards any changes you might have made    The best option is most likely to use an update panel as has been recommended   Another option  if you really need to do this client side  is to use a plain old  lt select gt  instead of an  lt asp ListBox gt   and to keep your list of items in a hidden field   When the page renders on the client you can populate it from a split of your text field contents     Then  when you are ready to post it  you repopulate the hidden field s contents from your modified  lt select gt    Then  of course  you have to split that again on the server and do something with your items  since your select is empty now that it s back on the server   All in all it s a pretty cumbersome solution that I would not really recommend  but if you really have to do client-side modifications of a listBox  it does work   I would really recommend you look into an updatePanel before going this route  however

User · Answer

If you fill the DropdownList through client side script then clear the list before submit the form back to server  then ASP NET will not complain and the security will be still on   And to get the data selected from the DDL  you can attach an  OnChange  event to the DDL to collect the value in a hidden Input or in a textbox with Style  display  none

User · Answer

Four minutes ago I received the same error  Then I have researched during one half hour like you  In all forums they are generally saying  add page enableEvent   false or true   Any solution proposed didn t resolved my problems until I found it  The problem is unfortunately an ASP NET button  I removed it two seconds ago  I tried to replace with  imagebutton   but it was also unacceptable  because it gave the same error    Finally I have replaced with LinkButton  it seems to be working

User · Answer

This error will show without postback  Add code    If  IsPostBack       do something

User · Answer

I had the same problem when modifying a ListBox using JavaScript on the client   It occurs when you add new items to the ListBox from the client that were not there when the page was rendered     The fix that I found is to inform the event validation system of all the possible valid items that can be added from the client   You do this by overriding Page Render and calling Page ClientScript RegisterForEventValidation for each value that your JavaScript could add to the list box   protected override void Render HtmlTextWriter writer        foreach  string val in allPossibleListBoxValues                Page ClientScript RegisterForEventValidation myListBox UniqueID  val             base Render writer       This can be kind of a pain if you have a large number of potentially valid values for the list box   In my case I was moving items between two ListBoxes - one that that has all the possible values and another that is initially empty but gets filled in with a subset of the values from the first one in JavaScript when the user clicks a button   In this case you just need to iterate through the items in the first ListBoxand register each one with the second list box   protected override void Render HtmlTextWriter writer        foreach  ListItem i in listBoxAll Items                Page ClientScript RegisterForEventValidation listBoxSelected UniqueID  i Value             base Render writer

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This error will show without postback  Add code    If  IsPostBack       do something

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you try something like that in your  aspx page    add      EnableEventValidation  false    you feel free to ask any question

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If you are using Ajax update panel  Add  lt Triggers gt  tag and inside it trigger the Button or control causing the postBack using  lt asp PostBackTrigger      gt

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Check you data of binded your controls  Some invalid data corrupt ValidateEvent

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As Nick B said and that worked for me you have to remove line breaks in some cases  Take a look at the code   -Wrong way    lt asp DropDownList ID  DropDownList1  runat  server  gt       lt asp ListItem Selected  True  gt              Item 1 lt  asp ListItem gt       lt asp ListItem gt              Item 2 lt  asp ListItem gt       lt asp ListItem gt              Item 3 lt  asp ListItem gt   lt  asp DropDownList gt    -Right way    lt asp DropDownList ID  DropDownList1  runat  server  gt       lt asp ListItem Selected  True  gt Item 1 lt  asp ListItem gt       lt asp ListItem gt Item 2 lt  asp ListItem gt       lt asp ListItem gt Item 3 lt  asp ListItem gt   lt  asp DropDownList gt    It only ocurred for me in IE10

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I was using datalist and I was getting the same error for my push button  I just use IsPostBack to check and fill my controls and the problem is solved  Great

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I had a similar issue  but I was not using ASP Net 1 1 nor updating a control via javascript  My problem only happened on Firefox and not on IE       I added options to a DropDownList on the PreRender event like this   DropDownList DD    DropDownList F FindControl  DDlista    HiddenField HF    HiddenField F FindControl  HFlista    string   opcoes   HF value Split   n    foreach  string opcao in opcoes  DD Items Add opcao     My  HF   hiddenfield  had the options separated by the newline  like this   HF value    option 1 n roption 2 n roption 3     The problem was that the HTML page was broken  I mean had newlines  on the options of the  select  that represented the DropDown   So I resolved my my problem adding one line   DropDownList DD    DropDownList F FindControl  DDlista    HiddenField HF    HiddenField F FindControl  HFlista    string dados   HF Value Replace   r        string   opcoes   dados Split   n    foreach  string opcao in opcoes  DD Items Add opcao     Hope this help someone

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Best option to do is use hidden field and do not disable event validation  also change every listbox  dropdownlist to select with runat server attribute

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What worked for me is moving the following code from page load to page prerender   lstMain DataBind    Image img    Image lstMain Items 0  FindControl  imgMain        Define the name and type of the client scripts on the page  String csname1    PopupScript   Type cstype   this GetType        Get a ClientScriptManager reference from the Page class  ClientScriptManager cs   Page ClientScript      Check to see if the startup script is already registered  if   cs IsStartupScriptRegistered cstype  csname1         cs RegisterStartupScript cstype  csname1    lt script language javascript gt  p       img ClientID       lt  script gt

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Check you data of binded your controls  Some invalid data corrupt ValidateEvent

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I worked around this exact error by not adding the ListBox to a parent Page Control Controls collection  Because I really didn t need any server-side functionality out of it  I just wanted to use it to output the HTML for a custom server control  which I did in the OnRender event handler myself  I hoped that using the control would save me from writing to the response my own html   This solution probably won t work for most  but it keeps ASP NET from performing the ValidateEvent against the control  because the control doesn t retain in memory between postbacks   Also  my error was specifically caused by the selected list item being an item that wasn t in the listbox the previous postback  Incase that helps anyone

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A simple solution for this problem is to use the IsPostBack check on your page load  That will solve this problem

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FYI I had the same issue with that error message and it was that I had 2 form tags on the same page  There was one in the Master page and one in the page itself  Soon as I removed the second form tag pair the problem went away

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The following example shows how to test the value of the IsPostBack property when the page is loaded in order to determine whether the page is being rendered for the first time or is responding to a postback  If the page is being rendered for the first time  the code calls the Page Validate method  The page markup  not shown  contains RequiredFieldValidator controls that display asterisks if no entry is made for a required input field  Calling Page Validate causes the asterisks to be displayed immediately when the page is rendered  instead of waiting until the user clicks the Submit button  After a postback  you do not have to call Page Validate  because that method is called as part of the Page life cycle       private void Page Load                 if   IsPostBack

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What worked for me is moving the following code from page load to page prerender   lstMain DataBind    Image img    Image lstMain Items 0  FindControl  imgMain        Define the name and type of the client scripts on the page  String csname1    PopupScript   Type cstype   this GetType        Get a ClientScriptManager reference from the Page class  ClientScriptManager cs   Page ClientScript      Check to see if the startup script is already registered  if   cs IsStartupScriptRegistered cstype  csname1         cs RegisterStartupScript cstype  csname1    lt script language javascript gt  p       img ClientID       lt  script gt

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We ran into this same issue when we were converting our regular ASPX pages to Content pages    The page with this issue had a  lt  form gt  tag within one of the Content sections  thus two form end tags were rendered at run time which caused this issue  Removing the extra form end tag from the page resolved this issue

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My problem was solved when cancel event at end of grid event at server side   protected void grdEducation RowEditing object sender  GridViewEditEventArgs e         do your processing           at end lt br   gt    e Cancel   true

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Ajax UpdatePanel makes it  and I think it s the easiest way  ignoring the Ajax postback overhead

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I had an experience with DataGrid  One of it s columns was  Select  button  When I was clicking  Select  button of any row I had received this error message       Invalid postback or callback argument   Event validation is enabled using  in configuration or        lt    Page EnableEventValidation  true     in a page   For security purposes  this feature verifies that arguments to postback or       callback events originate from the server control that originally rendered them   If the data is valid and expected  use the       ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation     I changed several codes  and finally I succeeded  My experience route   1  I changed page attribute to EnableEventValidation  false   But it didn t work    not only is this dangerous    for security reason  my event handler wasn t called  void Grid SelectedIndexChanged object sender  EventArgs e   2  I implemented ClientScript RegisterForEventValidation in Render method  But it didn t work   protected override void Render HtmlTextWriter writer        foreach  DataGridItem item in this Grid Items                Page ClientScript RegisterForEventValidation item UniqueID           foreach  TableCell cell in  item as TableRow  Cells                        Page ClientScript RegisterForEventValidation cell UniqueID               foreach  System Web UI Control control in cell Controls                                if  control is Button                      Page ClientScript RegisterForEventValidation control UniqueID                                     3  I changed my button type in grid column from PushButton to LinkButton  It worked    ButtonType  LinkButton    I think if you can change your button to other controls like  LinkButton  in other cases  it would work properly

User · Answer

One other way not mentioned here is to subclass ListBox  Ie    public class ListBoxNoEventValidation   ListBox        ClientEventValidation keys off the attribute System Web UI SupportsEventValidation  if you subclass it  unless you explicitly add it back in  it will never call the validation routine   That works with any control  and is the only way I ve found to  disable  it on a control by control basis  Ie  not page level

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1  EnableEventValidation  false                    It does not work for me    2  ClientScript RegisterForEventValidation    It does not work for me   Solution 1   Change Button ImageButton to LinkButton in GridView  It works   But I like ImageButton   Research  Button ImageButton and LinkButton use different methods to postback  Original article   http   geekswithblogs net mahesh archive 2006 06 27 83264 aspx  Solution 2   In OnInit     enter the code something like this to set unique ID for Button ImageButton    protected override void OnInit EventArgs e      foreach  GridViewRow grdRw in gvEvent Rows       Button deleteButton    Button grdRw Cells 2  Controls 1      deleteButton ID    btnDelete     grdRw RowIndex ToString                       Original Article    http   www c-sharpcorner com Forums Thread 35301

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I had an experience with DataGrid  One of it s columns was  Select  button  When I was clicking  Select  button of any row I had received this error message       Invalid postback or callback argument   Event validation is enabled using  in configuration or        lt    Page EnableEventValidation  true     in a page   For security purposes  this feature verifies that arguments to postback or       callback events originate from the server control that originally rendered them   If the data is valid and expected  use the       ClientScriptManager RegisterForEventValidation method in order to register the postback or callback data for validation     I changed several codes  and finally I succeeded  My experience route   1  I changed page attribute to EnableEventValidation  false   But it didn t work    not only is this dangerous    for security reason  my event handler wasn t called  void Grid SelectedIndexChanged object sender  EventArgs e   2  I implemented ClientScript RegisterForEventValidation in Render method  But it didn t work   protected override void Render HtmlTextWriter writer        foreach  DataGridItem item in this Grid Items                Page ClientScript RegisterForEventValidation item UniqueID           foreach  TableCell cell in  item as TableRow  Cells                        Page ClientScript RegisterForEventValidation cell UniqueID               foreach  System Web UI Control control in cell Controls                                if  control is Button                      Page ClientScript RegisterForEventValidation control UniqueID                                     3  I changed my button type in grid column from PushButton to LinkButton  It worked    ButtonType  LinkButton    I think if you can change your button to other controls like  LinkButton  in other cases  it would work properly

User · Answer

Best option to do is use hidden field and do not disable event validation  also change every listbox  dropdownlist to select with runat server attribute

User · Answer

Ajax UpdatePanel makes it  and I think it s the easiest way  ignoring the Ajax postback overhead

User · Answer

This was the reason why I was getting it   I had an ASP ListBox  Initially it was hidden  At client side I would populate it via AJAX with options  The user chose one option  Then when clicking the Submit button  the Server would get all funny about the ListBox  since it did not remember it having any options   So what I did is to make sure I clear all the list options before submitting the form back to the server  That way the server did not complain since the list went to the client empty and it came back empty   Sorted

User · Answer

In this case add id to the button in RowDataBound of the grid  It will solve your problem

User · Answer

If  you are using gridview and not bind gridview at pageload inside  ispostback then this error occur when you click on edit and delete row in gridview      protected void Page Load object sender  EventArgs e                if   IsPostBack                    bindGridview

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I know that this is a super-old post   Assuming that you are calling into your application  here is an idea that has worked for me    Implement the ICallbackEventHandler on your page Call ClientScriptManager GetCallbackEventReference to call your server side code As the error message states  you could then call ClientScriptManager RegisterForEventValidation   If you don t need total control  you could use an update panel which would do this for you

User · Answer

I had the same problem  two list boxes and two buttons   The data in the list boxes was being loaded from a database and you could move items between boxes by clicking the buttons   I was getting an invalid postback   turns out that it was the data had carriage return line feeds in it which you cannot see when displayed in the list box   worked fine in every browser except IE 10 and IE 11   Remove the carriage return line feeds and all works fine

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If  you are using gridview and not bind gridview at pageload inside  ispostback then this error occur when you click on edit and delete row in gridview      protected void Page Load object sender  EventArgs e                if   IsPostBack                    bindGridview

User · Answer

My problem was solved when cancel event at end of grid event at server side   protected void grdEducation RowEditing object sender  GridViewEditEventArgs e         do your processing           at end lt br   gt    e Cancel   true

User · Answer

If you fill the DropdownList through client side script then clear the list before submit the form back to server  then ASP NET will not complain and the security will be still on   And to get the data selected from the DDL  you can attach an  OnChange  event to the DDL to collect the value in a hidden Input or in a textbox with Style  display  none

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3  I changed my button type in grid   column from  PushButton  to    LinkButton   It worked      ButtonType  LinkButton   I think if   you can change your button to other   controls like  LinkButton  in other   cases  it would work properly    I wish I could vote you up  Amir  alas my rep is too low    I was just having this problem and changing this worked like a champ on my gridview   Just a little aside  I think the valid code is   ButtonType  Link   I suspect this is because when you click  edit   your edit changes to  update  and  cancel  which then change back to  edit  on submit   And these shifting controls make  net uneasy

User · Answer

you try something like that in your  aspx page    add      EnableEventValidation  false    you feel free to ask any question

User · Answer

I had the same problem when modifying a ListBox using JavaScript on the client   It occurs when you add new items to the ListBox from the client that were not there when the page was rendered     The fix that I found is to inform the event validation system of all the possible valid items that can be added from the client   You do this by overriding Page Render and calling Page ClientScript RegisterForEventValidation for each value that your JavaScript could add to the list box   protected override void Render HtmlTextWriter writer        foreach  string val in allPossibleListBoxValues                Page ClientScript RegisterForEventValidation myListBox UniqueID  val             base Render writer       This can be kind of a pain if you have a large number of potentially valid values for the list box   In my case I was moving items between two ListBoxes - one that that has all the possible values and another that is initially empty but gets filled in with a subset of the values from the first one in JavaScript when the user clicks a button   In this case you just need to iterate through the items in the first ListBoxand register each one with the second list box   protected override void Render HtmlTextWriter writer        foreach  ListItem i in listBoxAll Items                Page ClientScript RegisterForEventValidation listBoxSelected UniqueID  i Value             base Render writer

User · Answer

In this case add id to the button in RowDataBound of the grid  It will solve your problem

User · Answer

3  I changed my button type in grid   column from  PushButton  to    LinkButton   It worked      ButtonType  LinkButton   I think if   you can change your button to other   controls like  LinkButton  in other   cases  it would work properly    I wish I could vote you up  Amir  alas my rep is too low    I was just having this problem and changing this worked like a champ on my gridview   Just a little aside  I think the valid code is   ButtonType  Link   I suspect this is because when you click  edit   your edit changes to  update  and  cancel  which then change back to  edit  on submit   And these shifting controls make  net uneasy

User · Answer

if you change UseSubmitBehavior  True   to  UseSubmitBehavior  False  your problem will be solved   lt asp Button ID  BtnDis  runat  server  CommandName  BtnDis  CommandArgument   lt   Eval  Id    gt   Text  Discription  CausesValidation  True  UseSubmitBehavior  False    gt

User · Answer

The problem is that ASP NET does not get to know about this extra or removed listitem  You got an number of options  listed below     Disable eventvalidation  bad idea  because you lose a little of security that come with very little cost   Use ASP NET Ajax UpdatePanel   Put the listbox in the Updatepanel and trigger a update  if you add or remove listbox  This way viewstate and related fields get updates and eventvalidation will pass   Forget client-side and use the classic postback and add or remove the listitems server-side    I hope this helps

[.net] Invalid postback or callback argument. Event validation is enabled using '<pages enableEventValidation="true"/>'

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