This technote explains why An unexpected error has occurred 2001, please contact support is seen while updating IBM Rational Build Forge and how to resolve the error.
The previous attempt to update IBM Rational Build Forge failed.
This issue has been identified as a product defect and has been logged under APAR PM20721
Resolving the problem
Default install location shown below
BF_HOME= C:\Program Files\IBM\Build Forge
Remove directory keystore-back from BF_HOME/Manager, and restart the update process