Turned out customer's Load Data Warehouse job did not run successfully prior to the upgrade. Load Data Warehouse was failing with errors, which turned out to be due to few DWH views that were not having the latest DWH column names.The DWH views were not having CLARITY_UPDATED_DATE field as they should have done.
- Rollback to prior version
- Updated the DWH views on PPM database
- Ran Load Data Warehouse successfully
- Ran the upgrade
The Load Data Warehouse job must be ran successfully prior to starting upgrade.