Hi @ybaskar-temp_3339 ,
The "root cause" is relatively easy to answer. The error was occurring on the 10. Block 6.2 Upgrades.sql script, which is simply this:
IF OBJECT_ID('ActionGroups') IS NOT NULL EXEC sp_executesql N'
IF NOT EXISTS(SELECT * FROM [Configuration] WHERE [Key_Name] = ''Legacy.NoLegacyFeaturesDetected'' AND [Value_Text] = ''True'')
RAISERROR(''Cannot upgrade to BuildMaster 6.2 unless "Legacy.NoLegacyFeaturesDetected" in Advanced Settings is "True". This can be done by running the legacy features checker.'', 16, 1)
'
Basically it will simply crash unless Legacy.NoLegacyFeaturesDetected is not set to "True". The "Legacy Feature detector" should have set that to "True" if there were no legacy features detected... but perhaps it didn't?
Since you were able to bypass it, I wouldn't worry about it. In the "worse case", legacy data would have been purged during the delete.
Thanks,
Alana