When attempting to upgrade the Endpoint Protection Manager (SEPM), the database schema upgrade hangs at 0% or 1%.
The last entry in the Upgrade-0.log shows the following:
2020-12-11 09:11:33.693 THREAD 29 INFO: Upgrade >> Begin upgrading DB isolation READ_COMMITTED_SNAPSHOT...
2020-12-11 09:11:33.709 THREAD 29 INFO: DbUtil >> setDBtoReadSnapshort...
2020-12-11 09:11:33.709 THREAD 29 INFO: Begin setting DB isolation READ_COMMITTED_SNAPSHOT...
This hang can occur due to a known issue with SQL Server 2016 SP1 Cumulative Update 6 (CU6) when attempting to enable snapshot isolation when a server audit is enabled.
SQL Server 2016 SP1 Cumulative Update 6 (CU6)
To work around this issue, you can temporarily stop the audit before running the upgrade.
For more information, see the following Microsoft article: