a.	
SQL> @?/rdbms/admin/utlrp.sql

and get the list of the objects falling into: ORA-04023: Object ... could not be validated or authorized 

b.	
Check out XSDDIR directory has correct path. Check out XMLDIR directory has correct path. In case of need recreate the directories via conventional way 
or dbms_pdb.exec_as_oracle_script

c.	
SQL> alter pluggable database open upgrade;
SQL> @?/rdbms/admin/prvtnoqm.plb                             <- deinstall XDB, drop XDB user
SQL> delete from SYS.REGISTRY$ERROR where IDENTIFIER='XDB';
SQL> commit;

d.
Delete, by hands, all objects from the ORA-04023: Object ... could not be validated or authorized list. In case if need use dbms_pdb.exec_as_oracle_script.

e.
SQL> @?/rdbms/admin/catalog.sql
SQL> @?/rdbms/admin/catproc.sql
SQL> @?/rdbms/admin/catproc.sql                               <- yes, one more time
SQL> @?/rdbms/admin/utlrp.sql
SQL> alter pluggable database close;