IBM Cognos Configuration fails to save and start after upgrading from an earlier version of IBM Cognos 8 in the same directory (inplace upgrade). When you copy the decrypted cogstartup.xml file from the earlier install. When starting IBM Cognos Configuration, you receive the following message:

CAM-CRP-1280 An error occurred while trying to decrypt using the system protection key. Reason: javax.crypto.BadPaddingException: Given final block not properly padded

The Java Runtime Environment (JRE) has changed to 'C:/Program Files/cognos/c8/bin/jre/1.5.0'. The current cryptographic information is not compatible with the new JRE.

Regenerate option has no effect too:
CAM-CRP-1280 An error occurred while trying to decrypt using the system protection key. Reason: javax.crypto.BadPaddingException: Given final block not properly padded

Previous cryptographic information has not been deleted. 
 
 
Resolving the problem
Delete the caSerial and cogconfig.prefs files in the configuration directory. Also delete the three directories: csk, encryptkeypair, and signkeypair. Start IBM Cognos Configuration again.