ORA-60515
standby pluggable database string requires more recovery
Cause
An attempt was made to open a standby pluggable database (PDB) before recovery had applied sufficient redo from the primary to make the PDB consistent.
Action
Open the primary pluggable database, ensure redo shipping is enabled to the standby, and start managed recovery for the standby PDB. Allow recovery to catch up. Then cancel it and attempt the open operation again.