ASP.NET Application Goes to 500.21 ... until IIS Reset + Clear Tempoary ASP.NET Cache

Question

We're seeing an odd pattern in our QA Lab. We have two ASP.NET applications, each deployed on the same Windows 2008 SP2+ box. We have our App Pool running in a Domain Account, and set to never re-cycle. The same 1 App Pool is used by both applications.

After several hours of running fine, new users surfing to a page in our application get the IIS7 Error Page, with a 500.21 error.

If we do nothing but:

1) IISRESET 2) Change folder to c:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files and "rd" the 2 applications.

And then surf to our web applications, all is fine.

Then several hours later, however, the 500.21 errors return.

What strikes me as odd is the seeming relationship between clearing the "Temporary ASP.NET Files" folders and the problem going away. I've a practice of clearing the "Temporary ASP.NET Files" folders when installing a new version of our application(s), but not otherwise.

Does this relationship ring familiar to anyone? Is there some new-ish IIS7 feature at work here?

Text of Error:

Server Error in Application "DEFAULT WEB SITE/PAIS"
Internet Information Services 7.0
Error Summary
HTTP Error 500.21 - Internal Server Error
Handler "PageHandlerFactory-Integrated" has a bad module "ManagedPipelineHandler" in its module list
Detailed Error Information
Module IIS Web Core
Notification ExecuteRequestHandler
Handler PageHandlerFactory-Integrated
Error Code 0x8007000d
Requested URL http://localhost:80/PAIS/Admin.aspx

Physical Path C:\0_Georgia\GA_IS_100142\PortfolioArchiveImageServer\Admin.aspx
Logon Method Anonymous
Logon User Anonymous
Most likely causes:
• ASP.NET is not installed or incompletely installed.
• A configuration typographical error occured.
• Unfavourable pre-condition evaluation exists.
Things you can try:
• If ManagedPipelineHandler is missing, ensure that:
o ManagedEngine is in .
o ManagedPipelineHandler is in , with correct pre-conditions.
• Install ASP.NET.
• Ensure all system.webServer/handlers@modules are in system.webServer/modules@name.
• Review pre-conditions in the and sections.
Links and More Information IIS core does not recognize the module.
View more information »

Thanks in advance,

Howard Hoffman

Answer 1

Faced the same problem and the fix was easy.

1) Open visual studio 2010 command prompt.

2) Run the command aspnet_regiis.exe -i