Oracle Database Errors or Warnings from Error ORA-00000 to ORA-00024
ORA-00000: normal, successful completion
Cause: Normal exit.
ORA-00001: unique constraint (string.string) violated
Cause: An UPDATE or INSERT statement attempted to insert a duplicate key. For Trusted Oracle configured in DBMS MAC mode, you may see this message if a duplicate entry exists at a different level.
Action: Either remove the unique restriction or do not insert the key.
ORA-00017: session requested to set trace event
Cause: The current session was requested to set a trace event by another session.
Action: This is used internally; no action is required.
ORA-00018: maximum number of sessions exceeded
Cause: All session state objects are in use.
Action: Increase the value of the SESSIONS initialization parameter.
ORA-00019: maximum number of session licenses exceeded
Cause: All licenses are in use.
Action: Increase the value of the LICENSE MAX SESSIONS initialization parameter.
ORA-00020: maximum number of processes (string) exceeded
Cause: All process state objects are in use.
Action: Increase the value of the PROCESSES initialization parameter.
ORA-00021: session attached to some other process; cannot switch session
Cause: The user session is currently used by others.
Action: Do not switch to a session attached to some other process.
ORA-00022: invalid session ID; access denied
Cause: Either the session specified does not exist or the caller does not have the privilege to access it.
Action: Specify a valid session ID that you have privilege to access, that is either you own it or you have the CHANGE_USER privilege.
ORA-00023: session references process private memory; cannot detach session
Cause: An attempt was made to detach the current session when it contains references to process private memory.
Action: A session may contain references to process memory (PGA) if it has an open network connection, a very large context area, or operating system privileges. To allow the detach, it may be necessary to close the session’s database links and/or cursors. Detaching a session with operating system privileges is always disallowed.
ORA-00024: logins from more than one process not allowed in single-process mode
Cause: Trying to login more than once from different processes for ORACLE started in single-process mode.
Action: Logoff from the other process.
Above are list of Oracle Database Errors or Warnings from Error ORA-00000 to ORA-00024 received while performing certain operation against Oracle Database or related products.
What are Oracle Database Error Messages?
Oracle Error Messages may be returned while using products which are part of Oracle Database. Each Oracle Database Error or Warning Message mentioned above contains the Warning or Error Message Statement, a short explanation of the probable causes of the Error message, and a recommended action.
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Information about Oracle Database Error Messages or Warning Messages on Windows and Linux Operating Systems.