Error 503 and unable to access the MOSS site

Problem Description:
Gets error 503 and unable to access the MOSS site anymore after installing a German language pack

Error Message:

503, service is unavailable

Farm Configuration:

Product / Version / Bit: SP2010/14.0.6335.0000/X64
Operating System / Service Pack/Bit: Win 2k8 R2 /SP2/X64
Farm Configuration: 3 WFE
Hardware (Physical/virtual): Hyper-V
Database Used: SQL server 2008 R2

Troubleshooting Done:

1.   Tried accessing all the sites, just to make sure that the problem is restricted to one site or across the whole farm

2.   Reviewed SharePoint logs

3.   Checked event logs

4.   Checked the connectivity between SQL and SharePoint

5.   Checked the application pools are running or not

Cause:

Found out that the applications pools are all stopped and that’s why the sites not running.

It looks like when the language pack is installed and then the issue started happening.

Resolution:

Started the application pool one by one and tried accessing the sites

All sites are accessible now without any issues…

Additional Notes:

Noticed that one of the content DB (WSS_content_ABC) shows that a few sites are not upgraded to SharePoint 2010.

Detached the content Database and attached it back to the same web application, just to make sure that the DB gets upgraded.

Product Applies To:

SharePoint 2010

SharePoint 2007