AppPool Permission Issue with Accessing Report Server

Finally figure it out. My Reporting Services were configured to a local account while my Application Pool for IIS was configured to ApplicationPoolIdentity. I changed my Application Pool to LocalSystem and it fixed it. Hopefully this information will be useful to others as I wasted several hours figuring this out.

Another solution as mreyeros put it in the comment is to give the Browser permission to the IIS APPPOOL\DefaultAppPool user in Report Manager.

To do that you should open the Report Manager website (http:///Reports) in Home folder click Folder Settings -> Security, click New Role Assignment and input the IIS APPPOOL\DefaultAppPool as name, select permissions from the list.

Almost the same situation here except IIS and Report Server running on Windows Server 2008 R2. I used to have the asp.net application running with it's own application pool and everything worked. When I changed the application to the DefaultAppPool (due to a different problem), I got the permissions problem. I changed the Identity of the DefaultAppPool from ApplicationPoolIdentity to LocalSystem (in IIS, Advanced Settings) and it worked again.