Having a tough time with this issue. Not sure how but my ApplicationPoolIdentity is broken.
Currently I'm running IIS 8 on Windows 8 with Visual Studio 2012. When trying to debug an application from Visual Studio, or just navigating to the site in a browser I get the following error logged and a 503 error.
Application pool 'DefaultAppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool.
If I check out the Application error logs, I find the following error from the User Profile Service.
Windows cannot log you on because your profile cannot be loaded. Check that you are connected to the network, and that your network is functioning correctly.
DETAIL - The system cannot find the path specified.
Upon looking into the details I find that the User Profile Service is trying to load up a profile with the Id
S-1-5-82-3006700770-424185619-1745488364-794895919-4004696415
Now I opened up the registry to try and find the profile with that UserId. However there's nothing in the Profile list that helps.
So digging around a little more I've found that this issue can be resolved by either
A) Set the Load User Profile of the Application Pool to false.
B) Use a different account for the application pool.
C) Fix the account.
Seeing how this is the built in account, I'd prefer to fix the issue rather than fix the sympton.
What I have tried
My hunch
Somehow the ApplicationPoolIdentity got messed up. Is there any physical folders for the built-in accounts? I know that the Network and Local service profiles physical directories exist at C:\Windows\ServiceProfiles\. It is possible to recreate the ApplicationPoolIdentity profile? Or am I way off on what the real issue is?
C) Here is what i did to fix the account Go in regedit at key
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
There is a setting called "Default". You have to make sure that the data value point to an existing directory on the drive. By default it contains "%SystemDrive%\Users\Default". In my company the default is changed to a custom profile. Somehow, someone deleted that user profile. So when the defaultAppPool user tryed to create an accound for himself, it was unable to do so because windows cannot provide him with a default user profile.
You can also diagnose this error when looking at the Event Viewer under the Application folder. You will get a message of that type:
Windows cannot find the local profile and is logging you on with a temporary profile. changes you make to this profile will be lost when you log off.