ORA-00600: internal error code, arguments: [kziaVrfyAcctStatInRootCbk: !user], [APEX_PUBLIC_USER] after noncdb_to_pdb.sql

I found a bug last week after the creation of a PDB from NON-CDB in an empty 12.2 CDB with the noncdb_to_pdb.sql script :

After a successful conversion from NON-CDB to PDB, here is the error when trying to connect in the PDB as APEX_PUBLIC_USER :

In the PDB, I looked at the APEX users more closely and found that APEX_PUBLIC_USER and APEX_050000 were defined as common users. Even if they are not available in the root container, see the result of the CDB_USERS view below :

So to make a long story short, the noncdb_to_pdb.sql did not "convert" the APEX_PUBLIC_USER and APEX_050000 schemas as local users but left them as common users. A service request was raised and until an official fix is available, here is a workaround that Oracle Support gave to bypass the issue :

After this UNSUPPORTED modification to the data dictionary of the PDB, we were able to connect as APEX_PUBLIC_USER as it should be (without ORA-00600) :

Oracle will release a patch to correct the problem to the noncdb_to_pdb.sql script. The script will convert the common APEX users to local users only if they are not already available on the root container (default 12.2):

Bug 25979661 : ORA-00600: [KZIAVRFYACCTSTATINROOTCBK: !USER] [APEX_PUBLIC_USER]
https://support.oracle.com/epmos/faces/BugDisplay?id=25979661

Once again the workaround provided here is NOT SUPPORTED by Oracle and was used only to diagnose the problem.