Solution for ORA-01012: not logged on

ORA-01012: not logged on solution conn/as sysdba error ORA-01012: not logged on cause: shutting down the database is not followed by any of the close parameters.
Nomal ---> the database can be closed only when all connections are disconnected; transactional ---> actively disconnects after the transaction ends; immediate ---> actively disconnects the transaction and www.2cto.com abort ---> closes the database immediately, this operation is dangerous. It does not synchronize data, does not trigger the checkpoint, and the rollback segment is directly empty. It is equivalent to power failure, and the instance must be restored each time it is started. Therefore, the database is very slow. In this case, I quit sqlplus directly, causing the oracle file to be locked. When I start up again, the operation fails because the file is still locked. Error ORA-01012: not logged on. After restarting the service, I can use it. I have read the oracle error explanation, which is even more confusing to me. Although the problem has been solved, the production environment cannot be down at will. Therefore, this problem is to be continued... Www.2cto.com kill the oracle process or disable oracle ps-ef | grep ora_dbw0 _ $ ORACLE_SIDkill-9 pid restart oraclesqlplus sys as sysdbastartup;