Product:
Cognos Planning 10.1.1
Microsoft Windows 2008 R2 server
SQL 2008 server

Symptom:
When user try to open Cognos Planning Contributor node they get error message:

The application is now unavailable

Cause:
You must make the Cognos Planning application online inside Cognos Administration console after a GTP or a upgrade. This is different behavior than in previous versions of Cognos Planning.

Solution:
Log in to Cognos Planning Administration Console (CAC)
Mark you application in the left side.
Click on SET ON-LINE icon on the top left side.

Now you can ask the users to test to access the application again.