This error is triggered when trying to update a column in a table that is part of a correlated subquery involving the same table. This issue was encountered in Oracle databases of versions equal to or greater than 12.1 but below 12.2, with 12.1.0.2 being the confirmed affected version.

Description:
The error was caused by a regression that prevented the correct marking of the compare column in cases where there is a correlation column from the same table but a different view. This regression led to the ORA-00600 [qeselupdpre_20] error when executing certain update statements within the specified version range of Oracle databases.

Version Affected:
The problem affects Oracle database versions from 12.1 to 12.2, with the specific version 12.1.0.2 (Server Patch Set) confirmed to experience this issue. It’s crucial to note that this problem does not extend to versions 12.2 and above.

Workaround:
Unfortunately, there is no available workaround for the ORA-00600 [qeselupdpre_20] error in the affected versions of the Oracle database. Users encountering this issue are advised to proceed directly to the fix provided by Oracle.

Fixed:
The fix for the bug causing the ORA-00600 [qeselupdpre_20] error is first included in Oracle database version 12.2.0.1 (Base Release). Users experiencing this problem should consider upgrading their Oracle database to version 12.2.0.1 or later to resolve this issue.