Have a look of there any warning before this eror in the vent log, it sometimes throws a warning with a better description of the problem and then the error.
If you are still having the problem, try to add your app pool account into the local administrators group. I am not sure if it is needed, but it works for me most of the times.
The first thing I would do is go to the Application Pool properties, and re-enter the credentials for the Identity account.
Sometimes the stored password gets corrupted. Then, after a failed attempt or two at authenticating itself, it disables the Application Pool.
HTH...
I got this error. this is what worked for me:
Application Pool Rights
The K2 Workspace Service Account will require elevated permissions to run the application pool. Use the aspnet_regiis command to configure this. This tool ships with the .NET Framework, and takes the pain out of configuring all the required NTFS permissions, IIS_WPG group membership, security policy user rights assignments, and IIS metabase access rights. For more information, see the MSDN article on setting security rights for .NET Applications, at http://msdn2.microsoft.com/en-us/library/ms998297.aspx.
To use the aspnet_regiis command, perform the following steps:
- Open a command prompt (Start > Run > cmd)
- Change directories to the .NET Framework folder (C:WINDOWSMicrosoft.NETFrameworkv2.0.50727)
- Type aspnet_regiis -ga domainK2 Workspace Service Account and hit Enter
- After the command completes, type iisreset and hit Enter
If you are running the 64 bit version you will need to change the path to:
C:WINDOWSMicrosoft.NETFramework64v2.0.50727
