Creating pluggable database from seed, when pdb$seed in in mount state and open state.

SQL> show pdbs
 
    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       MOUNTED
         3 PDB1                           READ WRITE NO
         4 DEV                            READ WRITE NO

SQL> create pluggable database PDB2 ADMIN USER SALAM identified by Oracle create_file_dest='+DEV_DG_FLASH';
create pluggable database PDB2 ADMIN USER SALAM identified by Oracle create_file_dest='+DEV_DG_FLASH'
*
ERROR at line 1:
ORA-65036: Pluggable database PDB$SEED not open in required mode
 

SQL> alter pluggable database PDB$SEED open read only;
 
Pluggable database altered.
 
SQL> show pdbs
 
    CON_ID CON_NAME               OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY    NO
         3 PDB1                               READ WRITE  NO
         4 DEV15                             READ WRITE  NO

SQL> create pluggable database PDB2 ADMIN USER SALAM identified by Oracle create_file_dest='+DEV_DG_FLASH';       
 
Pluggable database created.
 
SQL> show pdbs
 
    CON_ID CON_NAME               OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY     NO
         3 PDB1                               READ WRITE   NO
         4 DEV                                 READ WRITE   NO
         7 PDB2                               MOUNTED