Winforms issue - Error creating window handle

Question

We are seeing this error in a Winform application   Can anyone help on why you would see this error  and more importantly how to fix it or avoid it from happening    System ComponentModel Win32Exception  Error creating window handle     at System Windows Forms NativeWindow CreateHandle CreateParams cp     at System Windows Forms Control CreateHandle      at System Windows Forms Control CreateControl Boolean fIgnoreVisible     at System Windows Forms Control CreateControl      at System Windows Forms Control OnVisibleChanged EventArgs e     at System Windows Forms ButtonBase OnVisibleChanged EventArgs e

User · Answer

This problem is almost always related to the GDI Object count, User Object count or Handle count and usually not because of an out-of-memory condition on your machine.

When I am tracking one of these bugs, I open ProcessExplorer and watch these columns: Handles, Threads, GDI Objects, USER Objects, Private Bytes, Virtual Size and Working Set.

(In my experience, the problem is usually an object leak due to an event handler holding the object and preventing it from being disposed.)

User · Answer

The out of memory suggestion doesn t seem like a bad lead   What is your program doing that it gets this error   Is it creating a great many windows or controls  Does it create them programatically as opposed to at design time  If so  do you do this in a loop   Is that loop infinite  Are you consuming staggering boatloads of memory in some other way   What happens when you watch the memory used by your application in task manager   Does it skyrocket to the moon   Or better yet  as suggested above use process monitor to dive into the details

User · Answer

This problem is almost always related to the GDI Object count, User Object count or Handle count and usually not because of an out-of-memory condition on your machine.

When I am tracking one of these bugs, I open ProcessExplorer and watch these columns: Handles, Threads, GDI Objects, USER Objects, Private Bytes, Virtual Size and Working Set.

(In my experience, the problem is usually an object leak due to an event handler holding the object and preventing it from being disposed.)

User · Answer

The out of memory suggestion doesn t seem like a bad lead   What is your program doing that it gets this error   Is it creating a great many windows or controls  Does it create them programatically as opposed to at design time  If so  do you do this in a loop   Is that loop infinite  Are you consuming staggering boatloads of memory in some other way   What happens when you watch the memory used by your application in task manager   Does it skyrocket to the moon   Or better yet  as suggested above use process monitor to dive into the details

User · Answer

I think it s normally related to the computer running out of memory so it s not able to create any more window handles   Normally windows starts to show some strange behavior at this point as well

User · Answer

Definitely too many handles memory leak issue     IT Jungles  System ComponentModel Win32Exception  Error creating window handle

User · Answer

I think it s normally related to the computer running out of memory so it s not able to create any more window handles   Normally windows starts to show some strange behavior at this point as well

User · Answer

Have you run Process Explorer or the Windows Task Manager to look at the GDI Objects  Handles  Threads and USER objects   If not  select those columns to be viewed  Task Manager choose View- Select Columns       Then run your app and take a look at those columns for that app and see if one of those is growing really large   It might be that you ve got UI components that you think are cleaned up but haven t been Disposed   Here s a link about this that might be helpful   Good Luck

User · Answer

Have you run Process Explorer or the Windows Task Manager to look at the GDI Objects  Handles  Threads and USER objects   If not  select those columns to be viewed  Task Manager choose View- Select Columns       Then run your app and take a look at those columns for that app and see if one of those is growing really large   It might be that you ve got UI components that you think are cleaned up but haven t been Disposed   Here s a link about this that might be helpful   Good Luck

User · Answer

I added a check that makes it work     if   form Handle ToInt32    gt  0        form Invoke method  args       it is always true  but the form throws an error without it  BTW  my handle is around 4 9 million

User · Answer

See this post of mine about  Error creating window handle  and how it relates to USER Objects and the Desktop Heap  I provide some solutions

User · Answer

Definitely too many handles memory leak issue     IT Jungles  System ComponentModel Win32Exception  Error creating window handle

User · Answer

The out of memory suggestion doesn t seem like a bad lead   What is your program doing that it gets this error   Is it creating a great many windows or controls  Does it create them programatically as opposed to at design time  If so  do you do this in a loop   Is that loop infinite  Are you consuming staggering boatloads of memory in some other way   What happens when you watch the memory used by your application in task manager   Does it skyrocket to the moon   Or better yet  as suggested above use process monitor to dive into the details

User · Answer

Have you run Process Explorer or the Windows Task Manager to look at the GDI Objects  Handles  Threads and USER objects   If not  select those columns to be viewed  Task Manager choose View- Select Columns       Then run your app and take a look at those columns for that app and see if one of those is growing really large   It might be that you ve got UI components that you think are cleaned up but haven t been Disposed   Here s a link about this that might be helpful   Good Luck

User · Answer

I think it s normally related to the computer running out of memory so it s not able to create any more window handles   Normally windows starts to show some strange behavior at this point as well

User · Answer

The windows handle limit for your application is 10 000 handles  You re getting the error because your program is creating too many handles  You ll need to find the memory leak  As other users have suggested  use a Memory Profiler  I use the  Net Memory Profiler as well  Also  make sure you re calling the dispose method on controls if you re removing them from a form before the form closes  otherwise the controls won t dispose   You ll also have to make sure that there are no events registered with the control  I myself have the same issue  and despite what I already know  I still have some memory leaks that continue to elude me

User · Answer

The windows handle limit for your application is 10 000 handles  You re getting the error because your program is creating too many handles  You ll need to find the memory leak  As other users have suggested  use a Memory Profiler  I use the  Net Memory Profiler as well  Also  make sure you re calling the dispose method on controls if you re removing them from a form before the form closes  otherwise the controls won t dispose   You ll also have to make sure that there are no events registered with the control  I myself have the same issue  and despite what I already know  I still have some memory leaks that continue to elude me

User · Answer

The out of memory suggestion doesn t seem like a bad lead   What is your program doing that it gets this error   Is it creating a great many windows or controls  Does it create them programatically as opposed to at design time  If so  do you do this in a loop   Is that loop infinite  Are you consuming staggering boatloads of memory in some other way   What happens when you watch the memory used by your application in task manager   Does it skyrocket to the moon   Or better yet  as suggested above use process monitor to dive into the details

User · Answer

Well  in my case it was definitely the USER Objects that were out of control  I looked in the Windows Task Manager and sure enough  the USER Objects count was at 10 000 exactly   I am dynamically embedding property and list sheets in Tab Pages by setting the Parent property of the property or list sheet s container panel to that of the Tab Page  I am conditionally recycling or re-creating the property and list sheet forms depending on the type of collection being listed or class type of the object being inspected   NB  In Delphi  all controls had an Owner and a Parent property  Even if one changed the Parent property of a control  it would still be disposed by its owner when the owning control got destroyed   In C  it seems that if a control e g  a Panel is programmatically reassigned from  say  a Form to a Tab Page by changing the Panel Parent property  calling Dispose   on the Form won t dispose the Panel  neither will calling Controls Clear   on the Tab Page  Even a direct call Panel Dispose   won t actually dispose it  unless its Parent is manually set to null beforehand

User · Answer

I got same error in my application I am loading many controls in single page In button click event i am  clearing the controls clearing the controls doesnot release the controls from memory So dispose the controls from memory  I just commented controls clear   method and include few lines of code to dispose the controls  Something like this  for each ctl as control in controlcollection  ctl dispose    Next

User · Answer

I got same error in my application I am loading many controls in single page In button click event i am  clearing the controls clearing the controls doesnot release the controls from memory So dispose the controls from memory  I just commented controls clear   method and include few lines of code to dispose the controls  Something like this  for each ctl as control in controlcollection  ctl dispose    Next

User · Answer

I think it s normally related to the computer running out of memory so it s not able to create any more window handles   Normally windows starts to show some strange behavior at this point as well

User · Answer

I added a check that makes it work     if   form Handle ToInt32    gt  0        form Invoke method  args       it is always true  but the form throws an error without it  BTW  my handle is around 4 9 million

User · Answer

Have you run Process Explorer or the Windows Task Manager to look at the GDI Objects  Handles  Threads and USER objects   If not  select those columns to be viewed  Task Manager choose View- Select Columns       Then run your app and take a look at those columns for that app and see if one of those is growing really large   It might be that you ve got UI components that you think are cleaned up but haven t been Disposed   Here s a link about this that might be helpful   Good Luck

User · Answer

The windows handle limit for your application is 10 000 handles  You re getting the error because your program is creating too many handles  You ll need to find the memory leak  As other users have suggested  use a Memory Profiler  I use the  Net Memory Profiler as well  Also  make sure you re calling the dispose method on controls if you re removing them from a form before the form closes  otherwise the controls won t dispose   You ll also have to make sure that there are no events registered with the control  I myself have the same issue  and despite what I already know  I still have some memory leaks that continue to elude me

User · Answer

The windows handle limit for your application is 10 000 handles  You re getting the error because your program is creating too many handles  You ll need to find the memory leak  As other users have suggested  use a Memory Profiler  I use the  Net Memory Profiler as well  Also  make sure you re calling the dispose method on controls if you re removing them from a form before the form closes  otherwise the controls won t dispose   You ll also have to make sure that there are no events registered with the control  I myself have the same issue  and despite what I already know  I still have some memory leaks that continue to elude me

User · Answer

Well  in my case it was definitely the USER Objects that were out of control  I looked in the Windows Task Manager and sure enough  the USER Objects count was at 10 000 exactly   I am dynamically embedding property and list sheets in Tab Pages by setting the Parent property of the property or list sheet s container panel to that of the Tab Page  I am conditionally recycling or re-creating the property and list sheet forms depending on the type of collection being listed or class type of the object being inspected   NB  In Delphi  all controls had an Owner and a Parent property  Even if one changed the Parent property of a control  it would still be disposed by its owner when the owning control got destroyed   In C  it seems that if a control e g  a Panel is programmatically reassigned from  say  a Form to a Tab Page by changing the Panel Parent property  calling Dispose   on the Form won t dispose the Panel  neither will calling Controls Clear   on the Tab Page  Even a direct call Panel Dispose   won t actually dispose it  unless its Parent is manually set to null beforehand

User · Answer

See this post of mine about  Error creating window handle  and how it relates to USER Objects and the Desktop Heap  I provide some solutions

[c#] Winforms issue - Error creating window handle

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