Application pool crashes with The identity of application pool, 'your app pool' is invalid

I have had an issue with an application pool crashing with an error saying the identity of the application pool is invalid. After changing the username and password multiple times it became clear an incorrect password is not an issue.

The application pool was actually running as a local user on the web server. In order for a user account to be used in an application pool it needs to be added to a local security group (I have never done this before so its certainly not always the case).

To get it working be sure that the account is a member of the local security group "IIS_WPG", for membership in the IIS_WPG group is needed to run the w3wp.exe worker process.

Application Pool stops when started

If you are using a custom identity for and application pool and get either of the following errors:

A failure was encountered while launching the process serving application pool 'WAP'. The application pool has been disabled.

or

The identity of application pool 'WAP' is invalid, so the World Wide Web Publishing Service can not create a worker process to serve the application pool. Therefore, the application pool has been disabled.

then you may need to grant some permissions to the account you are using.

Here is a list of things to try

• Add user to IIS_WPG group
• Add user to local admin group and adding the "Act as part of the os" right.
• run aspnet_regiis -ga "domain\user" on the user account you are using
• Check password
• Grant the Log on as service role in local / group policy

IIS Service Unavailable after setting 32bit (IIS 6.0)

I was having the "Service Unavailable" issue after I changed IIS to 32 bit mode. I found a solution that worked for me:

Our problem was that ASP.net was trying to run a 64 bit DLL, which failed after we reset IIS to 32 bit mode. All we needed to do was change the bitness of the ASP.net DLL to 32 bit mode. To do that, first turn on the server service. Once that service is running, run the following:

C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i -enable

This will reinstall ASP.NET with the appropriate bitness.

Configuring IIS to Run 32-bit Applications on 64-bit Windows (IIS 6.0)

To enable IIS 6.0 to run 32-bit applications on 64-bit Windows

1. Open a command prompt and navigate to the %systemdrive%\Inetpub\AdminScripts directory.
2. Type the following command:
   cscript.exe adsutil.vbs set W3SVC/AppPools/Enable32BitAppOnWin64 “true”
   
3. Press ENTER.

System.InvalidOperationException: Request format is unrecognized

If you try browsing to a web service asmx file and get the error message

System.InvalidOperationException: Request format is unrecognized

This may be becuase the required protocol is disabled in the web config file.

Here is a list of the possible protocols that could be missing from the web or machine.config.

Could not load file or assembly 'your assembly name' or one of its dependencies. An attempt was made to load a program with an incorrect format.

I just had a problem with the error message in IIS that reads:

Could not load file or assembly 'yourassemblyname' or one of its dependencies. An attempt was made to load a program with an incorrect format.
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.BadImageFormatException: Could not load file or assembly 'Sicon.API' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Now this message is not particularly helpful but after a while searching the problem was caused becuase the web application was installed on a 64bit server, in a 64bit application pool when the web application is compiled specifically for 32bit.

This is easy enough to fix by changing the application pool to allow 32bit applications from the advanced settings screen.

Ajax - 'sys' in undefined and the ASP.NET Ajax client-side framework failed to load

I had been struggling with this issue for a couple of days now. A small warning icon appears in Internet Exporer. Clicking on it shows a number of error messages.

1 - ASP.NET Ajax client-side framework failed to load
2 - 'sys' is undefined

I had checked the web.config file multiple times, all required sections were present and referencing the correct .net version dlls.

Finally after double checking absolutely everything I noticed that one of the handlers the web config was referencing did not have an extension mapping. This was the .axd extension. I added this in to IIS but the problem still occurred. Checking the handler mapping again I unchecked the 'Verify that the file exists' check box and retried the web page. This time it worked!

So in conclusion it turns out you do need to have the .axd extension mapping if it does not exist. And the check box to 'Verify the File Exists' must not be checked.