Unable to start debugging on the web server Could not start ASP NET debugging VS 2010 II7 Win 7 x64

Question

I am running Visual Studio 2010  as Admin   IIS 7 on Windows 7 x64  I am able to run the ASP NET web site in IIS 7 without debugging just fine  but when I press F5 to debug it  I get      Unable to start debugging on the web server  Could not start ASP NET debugging  More information may be available by starting the project without debugging    Unfortunately the help link is not helping me much and leads down a heck of a large tree of things   I checked the following    Security requirements     I don t recall having to do anything special before  The worker process in IIS7 is w3wp exe  It says that if it s running as ASPNET or NETWORK SERVICE I must have Administrator privileges to debug it  How do I find out if I need to change something here  Web site Property Pages   Start Options   Debuggers   ASP NET is checked  Use custom server is set to the URL of the site  which works fine without debugging   Debugging is enabled in web config  Application is using ASP NET 3 5  I want to move to 4 0 eventually but I have some migration to deal with   Application pool  Classing  NET AppPool  also tried DefaultAppPool     Any ideas where I can check next   Surely it shouldn t be that hard to install IIS  VS  create a web site  and start testing it   Thanks in advance

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Check if your website on IIS is not stop    I fixed it put my web site to run   D

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Instead of using the IIS  just use IIS Express

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Turns out that the culprit was the IIS Url Rewrite module  I had defined a rule that redirected calls to Default aspx  which was set as the start page of the web site  to the root of the site so that I could have a canonical home URL  However  apparently VS had a problem with this and got confused  This problem did not happen when I was using Helicon ISAPI Rewrite so it didn t even occur to me to check   I ended up creating a whole new web site from scratch and porting projects files over little by little into my solution and rebuilding my web config until I found this out  Well  at least now I have a slightly cleaner site using  NET 4 0  so far  hopefully I won t run into any walls --but what a pain

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Dan   In addition to Aaron s suggestions  try the following   Check that integrated windows authentication is selected in your IIS website Can you debug using Cassini instead of IIS

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I was getting the same error message in VS 2012  but was not running as Administrator   When I ran the app as administrator  I got a different and slightly more helpful message  which I was able to figure out    HTH

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For the benefit of others  in my case I had configured the application pool to use my windows credentials in order to access a network resource share  Since debugging the solution last I had reset my windows password  Changed password stored in app pool and bada bing

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Had the same issue trying to debug a DNN  Dot Net Nuke  module  Turned out you need to have compilation debug  true     lt compilation debug  true  strict  false  targetFramework  4 0  gt     in your web config  By default it is false in DNN  Original source here  http   www dnnsoftware com forums forumid 111 postid 189880 scope posts

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If App Pool has trouble restarting or simply doesn t want to restart  verify if windows made recent update on ASP NET v4 0 or other App Pool  That is what happend in my case  I simply restarted my computer  then restarted ASP NET v4 0 App Pool and everything was working again

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Just finally fixed this for my single solution that was having this   Two of the projects in the solution were set as sites in IIS   I went in and enabled ASP Net Impersonation under Authentication for both projects   and VIOLA   FINALLY  no more of this annoying error

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Here is what I did to clear the error you noted  Locate the web folder for the app within the file system  go to Properties  Security click the Advanced button then click the Owner tab  click the Edit button and change the owner  with the correct permissions  of the folder and checked the  Repalce owner on subcontainers and objects  checkbox  Click  Apply  and then I was in business  able to debug    Hope this works for someone else

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had same issue  If you have SSL certificate installed on IIS and if you are trying to debug it from Visual Studio then you need to set your application on IIS to ignore certificate

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I had the same problem in Visual Studio 2012 and 2013 on Windows 8 1  For me the fix was to add Windows Authentication to IIS using  Turn Windows features on or off

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Had the same problem with Windows 10 when turned on all IIS windows features  Switched to Windows 8 1 and got problem again   The root was in web site name  http   MySite local   not related to OS version     And solution is simple    Edit hosts file in  SystemRoot  System32 drivers etc  Add line with ip binding  127 0 0 1 MySite local

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I found this issue too but it was most similar to what  Kirk explained and URL rewriting   In my case someone had checked in this change to the web config file for a MVC project    lt system webServer gt       lt security gt           lt requestFiltering gt               lt fileExtensions gt                   lt add fileExtension   aspx  allowed  false    gt               lt  fileExtensions gt           lt  requestFiltering gt       lt  security gt   lt  system webServer gt    Because  aspx file extensions were not allowed on the web server  the  debugattach aspx URL was denied  preventing the debugger from running  Once I removed this configuration it worked again

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I had faced the same problem but it was on Visual studios s own web development server instead of IIS The get around is to uncheck the option in Web tab under project properties  Apply server settings to all users store in project file   Hope it will save some one s valuable time

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Visual Studio  when starting up  will  for some reason  attempt to access the URL       debugattach aspx   If you have a rewrite rule that redirects  or otherwise catches   say   aspx files  somewhere else then you will get this error   The solution is to add this section to the beginning of your web config s  lt system webServer gt   lt rewrite gt   lt rules gt  section    lt rule name  Ignore Default aspx  enabled  true  stopProcessing  true  gt       lt match url   debugattach  aspx    gt       lt conditions logicalGrouping  MatchAll  trackAllCaptures  false    gt       lt action type  None    gt   lt  rule gt    This will make sure to catch this one particular request  do nothing  and  most importantly  stop execution so none of your other rules will get run   This is a robust solution  so feel free to keep this in your config file for production

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For my scenario it was changes to the httpErrors section in web config  setting it like this    lt httpErrors mode  Custom  gt     caused the  Unable to start debugging on the web server  issue   Setting it back to the previous value of  DetailedLocalOnly  fixed the issue   Digging a little deeper I discovered that it was actually just the 401 error setting that was causing this    lt httpErrors mode  Custom  gt        lt error statusCode  401  prefixLanguageFilePath    path   masterpages 500 html  responseMode  ExecuteURL    gt   lt httpErrors mode  Custom  gt     Commenting out the 401 error line fixed the issue as well  I went with that since I can then maintain the custom error handling and start with debugging   I still have no idea why this is happening

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Try going to IIS and checking to make sure the App Pool you are using is started  A lot of times  you will produce an error that shuts down the app pool  You just need to right click and Start and you should be good to go

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I had this error come up today due to a defect in code that was posting back a tremendous amount of times causing IIS to be flooded with requests   This essentially locked up IIS and so when I tried to debug  it  timed out  trying to start the debugger   I simply restarted IIS  which took a few minutes  and it solved the issue   I sure do wish this error was less generic  seems like there are several different ways to produce it

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I had this problem and eventually realized that I ASP net is not registered properly with IIS  This can happen when IIS server is installed before Visual Studio  To fix this issue  use the command aspnet regiis -i Further information can be found in the link

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remove sting like this  targetFramework  4 0  in web config or change AppPool to appropriate framework version

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Plase check application pool  if it is stoped  restart it

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I have exactly the same problem after implementing the rewrite module   If I remove the rewrite entries from my web config file  debugging works perfectly   To get around this  I just to comment out the rewrite tags while debugging  like this      lt rewrite gt       lt rules gt           lt rule name  LowerCaseRule 1  stopProcessing  true  gt               lt match url   A-Z   ignoreCase  false    gt               lt action type  Redirect  url   ToLower  URL      gt           lt  rule gt           lt rule name  RedirectDefault aspx 1  stopProcessing  true  gt               lt match url      default aspx    gt               lt action type  Redirect  url   R 1   redirectType  Permanent    gt           lt  rule gt       lt  rules gt   lt  rewrite gt    I then remove the comments after debugging   Must be an bug in visual studio 2010

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If ApplicationPool Identity is set custom account and computer s password is changed  you have to update your password

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I had the same issue and found that it was caused because i had a character mistakenly typed in my Web config after the end tag  My Web config looked like this right at the end   lt  section gt h  The  h  was an extra character after the closing tag

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I got the same error since Application pool was stopped in IIS  After starting the App Pool  the issue was resolved

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I had the same problem  All the answers above did not work for me  The solution was to delete the bin and obj folder manually

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Be sure your site s Application Pool uses the correct framework version  I got the  Unable to start debugging  error on an ASP Net 2005 site  It was incorrectly using the DefaultAppPool on Windows 7  which I believe was using  Net Framework 4   I created a new a App Pool based on  Net Framework 2 and assigned it to the problem web site  After that debugging worked fine

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I got this same error recently and in my case it turned out that there were duplicate MIME types   I had recently added two that didn t show up in the list initially   IIS let me add them and it was only when I decided to check the MIME types for the site again as part of my diagnostic process that I got an error in IIS as well   It referenced duplicates in web config   Once I went back into the web config file I noticed that a new section called  had been added  which included the two recently-added MIME types   Deleted that section and life is good again   Hoping this may help others who haven t managed to fix the issue with any of the other suggestions

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Uninstalling the IIS UrlScan Extension solved the problem for me

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I had the same problem when I created application in Visual Studio  and then in properties created virtual directory for use with local IIS  If someone has this error it is because VS creates application under wrong AppPool  i e  under AppPool which doesn t suit your needs  If this is the case  go to IIS Manager  select App  Go to Basic settings and change AppPool for App and you are good to go

[asp.net] Unable to start debugging on the web server. Could not start ASP.NET debugging VS 2010, II7, Win 7 x64

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