ORA-01586: database must be mounted EXCLUSIVE and not open for this operation

As this message clearly explains, this error means that the operation you are going to perform that returned this error, needs database to be mounted EXCLUSIVELY - by only one instance. In my case, I was trying to drop a RAC database when I faced ORA-01586. I realized that the other instance of my RAC database is still up and it is needed that all the instances of a RAC database should be down before we can drop a database.

SQL> shutdown immediate ORA-01109: database not open Database dismounted. ORACLE instance shut down. SQL> startup restrict mount ORACLE instance started. Total System Global Area 2.5655E+10 bytes Fixed Size                  2265224 bytes Variable Size            1.3489E+10 bytes Database Buffers         1.2147E+10 bytes Redo Buffers               16896000 bytes Database mounted. SQL> show parameter db_name NAME                                 TYPE        VALUE ------------------------------------ ----------- ------------------------------ db_name                              string       mydb SQL> drop database; drop database * ERROR at line 1: ORA-01586: database must be mounted EXCLUSIVE and not open for this operation SQL>

Shutting down the remaining instance and then re-execution of DROP DATABASE command worked for me, and database was dropped successfully. You may face same error during some other command execution, and in case of a RAC database, you should make sure that only one instance is up and running where you are executing your respective command.