while upgrading a database from Oracle 12cR1 to 12cR2….the following errors were thrown in the alert log file:

Errors in file /oraclex/orcl/diag/rdbms/orcl/orcl/trace/orcl_m000_125839.trc (incident=708075):

ORA-00600: internal error code, arguments: [Migrate Relation Failure], [], [], [], [], [], [], [], [], [], [], []

ORA-48254: Migration Error [dbgrmmdmr_max_length_change] [PDB_SPACE_MGMT] [2] [66] [32] [9]

Incident details in: /oraclex/orcl/diag/rdbms/orcl/orcl/incident/incdir_708075/orcl_m000_125839_i708075.trc

Use ADRCI or Support Workbench to package the incident.

This is due to old ADR setup, so you need to reset ADR location

SQL> show parameter diagnostic_dest
SQL> ALTER SYSTEM SET diagnostic_dest=/orcl/ora23/diagnostic/ scop=spfile;