Error in Step 4 during database upgrade from AX 2012 R2 to D365 8.1

I am running database upgrade package in Tier2 Sandbox environment to upgrade AX 2012 R2 to D365 version 8.1 and during Step 4 - prereq for AX6 data upgrade, I am getting following error message:

Internal error occurred executing stored procedure when creating session for the AOS. I checked event viewer and found following error :

The description for Event ID 117 from source Dynamics Server Database Synchronizer cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event: 

Object Server Database Synchronizer: 
[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Cannot insert the value NULL into column 
'LOGINDATETIMETZID', table 'zzxepa-test_axdb_7a123c58ee20b413.dbo.SYSSERVERSESSIONS'; column does not 
allow nulls. INSERT fails.
{call CREATESERVERSESSIONS(?,?,?,?,?,?)}
session 1 (-AOS-)

Does anyone have any clue what could have gone wrong or how to fix this issue ?