Can't rename PDB after upgrade to 18.10

after I upgraded a 12.1 instance to 18.10 everything was running fine.

I wanted to rename a PDB to a different name, but when I run

    alter session set container = cdb$root;     alter pluggable database old_pdb close immediate;     alter pluggable database old_pdb open restricted;     alter session set container=old_pdb;     alter pluggable database old_pdb rename global_name to new_name;

this results in:

    SQL> alter pluggable database old_pdb rename global_name to new_name;     alter pluggable database old_pdb rename global_name to new_name     *
    ERROR at line 1:
    ORA-01405: fetched column value is NULL

Searching through MOS reveals a bug where a NULL value in the REGISTRY$.VERSION causes this - typically caused by a non-upgraded APEX installation (Doc ID 2523458.1)

So I removed APEX completely from that PDB (I don't need it anyway), but the error still happens.

Re-checking registry$ reveals no entry with a NULL value for the VERSION column.

However, the columns ORG_VERSION_FULL and PRV_VERSION_FULL are NULL for all entries - but that seems to be normal

The alert log contains the following when this happens:

    OLD_PDB(3):Endian type of dictionary set to little     2020-08-13T14:07:48.523702+02:00
    OLD_PDB(3):Database Characterset for OLD_PDB is AL32UTF8     OLD_PDB(3):ORA-1405 signalled during:     alter pluggable database OLD_PDB rename global_name to oradb...

Is there anything else I can do apart from not renaming the PDB?

This is running on CentOS 6.9 if that matters (it's a development and test environment, not production)

Thomas

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