Oracle Database 12c - convert PDB from read only to read write

How to convert pdb from read only to read write

SQL> show pdbs

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 DX12P                          READ ONLY  NO

SQL> alter pluggable database dx12p open;
alter pluggable database dx12p open
*
ERROR at line 1:
ORA-65019: pluggable database DX12P already open


SQL> alter pluggable database dx12p close immediate;

Pluggable database altered.

SQL> alter pluggable database dx12p open;

Pluggable database altered.

SQL> show pdbs

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 DX12P                          READ WRITE NO
         4 DX12P1                         READ WRITE NO