To remove the restricted mode from PDB, we can do it either in CDB or PDB. In fact, disabling the restricted mode is just a reverse process of enabling restricted mode of a PDB.
If it was a newly cloned or created PDB and it fell in restricted mode every time you tried to open it normally, then you should check the following post: How to Resolve "Warning: PDB altered with errors.".
Remove PDB Restricted Mode in CDB
Disabling the restricted mode of a PDB in the root container is the easiest way to do it.
Check Current Status
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 ORCLPDB READ WRITE YESDisable Restricted Mode
Here we use OPEN FORCE to leave restricted mode and go back to normal READ WRITE.
SQL> alter pluggable database ORCLPDB open force;
Pluggable database altered.Check Current Status Again
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 ORCLPDB READ WRITE NOAs you can see, RESTRICTED is now NO.
Remove PDB Restricted Mode in PDB
In a PDB, you can also leave the restricted mode like a normal, typical database (non-CDB).