Oracle® Database 11g / 12c / 18c error codes ORA-00024: logins from more than one process not allowed in single-process mode

ORA-00024: logins from more than one process not allowed in single-process mode

Oracle Error Code: ORA-00024

Cause: Trying to login more than once from different processes for ORACLE started in single-process mode.

Action: Logoff from the other process.