ApplicationPool is not creating a new user profile

Question

When creating a new website or just a new ApplicationPool, IIS should create a new Windows user-profile (via WAS). Unfortunately this is not working anymore when I set the identity of the ApplicationPool to ApplicationPoolIdentity.The pool is immediately crashing as it is not finding the according user-profile (found the error inside the windows event-viewer). When I toggle loadUserProfile to false, the website and the ApplicationPool are running fine, but I don't know why this is not working anymore, since it has been working for months without problems. I reinstalled IIS and cleared the users which were created before but nothing is working. IIS is simply not creating a new user profile and so the ApplicationPool keeps crashing.

These are the error messages I receive from the Windows Event-Manager (translated):

Erorr-ID 1511: The local user profile has not been found, you are going to be logged in with a temporary user profile.

Error-ID 1500: You could not be logged in, because the local stored user profile could not be loaded.

Answer 1

Erorr-ID 1511: The local user profile has not been found, you are going to be logged in with a temporary user profile.

Error-ID 1500: You could not be logged in, because the local stored user profile could not be loaded.

Possible reasons include:

1. Your local profile is corrupt.
2. You no longer have adequate privileges to the profile folders.
3. All changes made to the temporary profile will be lost when you log off.

Below is a workaround I've seen in a blog, I'm not sure if it will work in your case, just for reference.

1. Reboot your machine and log in as a different user. Make sure the different user account is an administrator (added to the administrators group). Or, if you know how to log in, you can log in to Safe Mode.
2. Open Explorer and open C:\Users. Delete the "problematic" user profile directory and the "Temp" directory.
3. Run Registry Editor (RedEdit.exe)
4. Go to the following location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
5. You need to find the correct SID and delete it. To make sure you are removing the correct one, check the key ProfileImagePath which has the profile path.
6. Restart the computer and log in as the user as before.

If this doesn't solve your problem, I think Debug Diagnostics Tool (DebugDiag) can be a lifesaver. When the server hangs, crashes or performance is low, it is usually necessary to grab the server's thread stack (Thread Dump) for subsequent analysis. IIS Application Pool Crash and Debug Diag

So I suggest you open a case via: https://support.microsoft.com, there will be professional technicians to assist you in grabbing the dump file and analyzing it.