HTTP Error 503 The service is unavailable App pool stops on accessing website

Question

There are number of posts on this and I have tried many a things by now  But to no avail  Myself a Winforms Developer basically  started working on this Web stuff few days back as my company is taking Web initiatives   I have a ASP Net project and I want to host it on local IIS  In Project properties - gt  Web settings I chose Use Local IIS Server and gave a url as localhost MyApp  I tried accessing it on my firefox browser and received error as HTTP Error 503  The service is unavailable   Previously I got many other errors and I one by one fixed them all  But struck with this one  These are the settings I have in my project   Application Pool set to ASP Net v4 0 Classic App Pool Enable 32 bit Application property is true App Pool is started Project build property set to Any CPU for Target framework   But I would like to mention a weird behavior  Following is something that I am facing   Application Pool is Started I try to access my local website  by giving url as localhost MyApp  I receive the error as HTTP Error 503  The service is unavailable Application Pool is Stopped   I have seen following link and I have already tried it  For the above behavior I reached here  According to this link  Computer name should not have   in it  I don t have any   in my Computer name but do have - in it  Also my domain name contains   in it  Moreover I can t change these settings as its my office laptop and our TFS settings are bound to our Domain and Computer Names   Can anyone help me to understand whats happening  Please guide me  Thanks   Edit  I have following code in Global asax  Application BeginRequest method is empty in same file   protected override void Application Start object sender  EventArgs e        base Application Start sender  e       String  path   String Concat System AppDomain CurrentDomain RelativeSearchPath                                                System Environment GetEnvironmentVariable  PATH         System Environment SetEnvironmentVariable  PATH    path  EnvironmentVariableTarget Process       MyAppLog Initialize        MyAppLog WriteMessage  Application Started        Update  As per the suggestions in Comment  I am able to run the website from Cassini

User · Answer

I had the same issue with iis 8 5  After searching the eventViewer under windows Logs-- applications  I realized that I m having a permission error for the machine config file of the  net framework located at  C  Windows Microsoft NET Framework64 v4 0 30319 Config machine config   Giving it a permission for IIS IUSRS solved my problem  right click the file-- properties-- security-- edit-- add-- IIS IUSRS

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One possible reason this might happen is that you don t have enough disk space in your server machine  You can find more information in event viewer  if such thing happen  just stop the IIS  clean some free disk space and restart the IIS and then start the App Poll

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For anyone coming here with Windows 10 and after updating them to Anniversary update  please check this link  it helped me   https   orcharddojo net blog troubleshooting-iis-apppool-crashes-status-503-after-windows-10-anniversary-update  In case link goes down  If your Event log shows that aspnetcore dll  rewrite dll  most often  but could be others as well  failed to load  you have to repair the missing items    Here are two specific issues we ve experienced so far and how to fix them  but you may bump into completely different ones    C  WINDOWS system32 inetsrv rewrite dll   reference      Go to  Programs and Features   Win X  F  and repair  IIS URL Rewrite Module 2    C  WINDOWS system32 inetsrv aspnetcore dll   reference      Go to  Programs and Features   Win X  F  and repair  Microsoft  NET Core 1 0 0 - VS 2015 Tooling

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In my case error message displaed in Windows Event Viewer - gt  Windows Logs - gt  Application was  quot The Module DLL C  Windows system32 inetsrv rewrite dll failed to load  The data is the error  quot  Uninstalling rewrite module via installer solved the problem  I wasn t using any rewrite rules so I uninstalled  rewrite module  Reinstalling  the module may help the problem as well

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Just to add to these Anniversary Update issues  thanks Microsoft  if the file you are missing is cgi dll  ie your Event Viewer has  The Module DLL C  WINDOWS System32 inetsrv cgi dll failed to load   The data is the error    Then to fix this    Go to IIS Manager Select the very top row in the Connections panel  typically your PC name  At the very bottom of the right panel  under Management  you should have Web Platform Installer Once that loads  select Products In the search type in cgi then hit  lt Enter gt  Select IIS  CGI then click Add on the right and finally Install on the bottom After installing it should force you to restart your PC and you should be fixed

User · Answer

Changing  Managed Pipeline Mode  from  Classic  to  Integrated  worked for me  It can be changed at Application Pools -  Basic Settings

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In addition to the steps outlined at this link from Orhan s answer  you may need to additionally remove the native module by going to IIS Manager   Server Root   Modules   Configure Native Modules  Select MfeEngine and then select Remove

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Will this answer Help you   If you are receiving the following message in the EventViewer  The Module DLL aspnetcorev2 dll failed to load  The data is the error   Then yes this will solve your problem  To check your event Viewer  press Win R and type  eventvwr  then press ENTER  On the left side of Windows Event Viewer click on Windows Logs - gt  Application  Now you need to find some ERRORS for source IIS-W3SVC-WP in the middle window    if you receiving the previous message error then solution is    Install Microsoft Visual C   2015 Redistributable 86x AND 64X  both of them  Source

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For my situation is that my login password changed  while the application pool still uses the old one  So just click the  Advanced Settings  of your application pool and reset your  Identity

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I had a similar issue  all my app pools were stopping whenever a web request was made to them  Although I was getting the following error in the Event Viewer      The worker process for application pool  appPoolName  encountered an   error  Configuration file is not well-formed XML   trying to read   configuration data from file       C  inetpub temp apppools appPoolName appPoolName config   line   number  3    The data field contains the error code    Which told me that there were errors in the application config at      C  Windows System32 inetsrv config applicationHost config   In my scenario  I edited the web config on deploy with an element IIS clearly dislikes  the applicationHost config scraped the web config and inserted this bad element and wouldn t resolve until I manually removed it

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I was experiencing this error and in my case the cause was that some time ago I modified the user password  and the 503 error didn t appears till I restarted the application pool    So I fixed it setting the new password on Applications Pools   Advanced Settings   Identity           Set      Password   Confirm Password

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In my case I checked event logs and found error was  Cannot read configuration file   trying to read configuration data from file         line number  0    The data field contains the error code   The error code was 2307   I deleted all files in C  inetpub temp appPools and restarted the iis  It fixed the issue

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I was facing the same problem  and debugged it using the event logs  First it said that    The description for Event ID 5059 from source Microsoft-Windows-WAS cannot be found    I then turned on WAS using turn windows features on off  Then i saw this in eventvwr  Microsoft-Windows-DistributedCOM cannot be found    Finally I gave up and deleted the App Pool  that used to stop on accessing the website  and created it again  as it is  This resolved the problem

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I had a similar issue  I solved it by adding my user to the  Log on as a batch job  policy under  Local Security Policy     Local Policies     User Rights Assignment

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One possible reason this might happen is that the Application Pool in IIS is configured to run under some custom account and this account either doesn t exist or a wrong password has been provided  or the password has been changed  Look at the advanced properties of the Application Pool in IIS for which account it uses    Also the Event Log might contain more information as to why the Application Pool is stopping immediately on the first request

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Ok  I have another solution for one specific case  if you use WINDOWS 10  and you updated it recently  with Anniversary Update package  you need to follow the steps below    Check your Windows Event Viewer - press Win R and type  eventvwr  then press ENTER  On the left side of Windows Event Viewer click on Windows Logs -  Application  Now you need to find some ERRORS for source IIS-W3SVC-WP in middle window  Probably you will see message like       The Module DLL   path-to-DLL lt  lt  failed to load   The data is the error     You have to go to Control Panel -  Program and Features and depending on which dll cannot be load you need to repair another module    for rewrite dll - find IIS URL Rewrite Module 2 and click Change- Repair for aspnetcore dll - find Microsoft  NET Core 1 0 0 - VS 2015 Tooling     and click Change- Repair   Restart your computer

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If you have McAfee HIPS and if you see the following error in event viewer application log        The Module DLL C  Windows System32 inetsrv HipIISEngineStub dll failed to load        The data is the error      Then the following resolved the issue in my case  https   kc mcafee com corporate index page content amp id KB72677 amp actp LIST  Quote from the page         Click Start  Run  type explorer and click OK    Navigate to   windir  system32 inetsrv config   Open the file applicationHost config as Administrator for editing in Notepad    Edit the  lt globalModules  section and remove the following line     lt add name  MfeEngine  image   windir  System32 inetsrv HipIISEngineStub dll       Edit the  lt modules  section and remove the following line     lt add name  MfeEngine            After you have finished editing the applicationHost config file  save the file  then restart the IIS server using iisreset or by restarting the system

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Most of Time  it was occured due to AppPool Setting   Check the following to resolve this   Check Apppool service is running   Check Identity of AppPool  Enter the new password if it has changed for that identity    The following Images show these setting in IIS

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If you can run the website in Visual Studio debugger  then might be able to see where in your code the application pool is crashing   In my case  it was a function being called recursively an unlimited number of times  and that caused a stack overflow   Note  the Windows event log and the IIS logs were not helpful to diagnose the problem

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When I first time add the service and created the app pool for it  I did  iisreset  from command prompt  and it worked

[c#] HTTP Error 503. The service is unavailable. App pool stops on accessing website

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