IIS 7 and Above
FPSE 2002 on Win 2008 server --> Service Unavailable
Re: FPSE 2002 on Win 2008 server --> Service Unavailable
Jul 22, 2008 11:38 PM|Zhao Ji Ma - MSFT|LINK
You will encounter Servie Unavailable error when the application pool is not running, the full error message is like the following.
HTTP Error 503. The servie is unavailable.
For Microsoft Sharepoint Administration site, please make sure MSSharePointAppPool has been started. Select
Application Pools node in IIS 7 Manager, you can see an application pool call MSSharePointAppPool. The status field indicates the current status of the application pool. Click MSSharePointAppPool, then you will see
Start/Stop actions under the Application Pool Tasks on the pane of the right side in IIS 7 Manager.
You may also receive Service Unavailable error when concurrent request limit exceeded, but it doesn't looks like your case, you can see
The HTTP Status code in IIS 7.0 for reference.