Error code
SQL Server 18456
SQL SERVER18456
Database Error Code· An error code returned by a database server such as PostgreSQL or MySQL.
What it means
login failed for user — authentication rejected.
How to fix it
- Verify the username and password in the connection string.
- Unlock or re-enable the SQL Server login with ALTER LOGIN <name> ENABLE.
- Check the SQL Server error log for the exact state code in the 18456 message for a more specific diagnosis.
Not affiliated with SQL Server. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More SQL Server codes
- 10054an existing connection was forcibly closed by the remote host — network reset
- 102incorrect syntax near — the parser encountered an unexpected token
- 1105could not allocate space for object — the filegroup or disk is full
- 1205transaction was deadlocked and chosen as the deadlock victim — rolled back
- 156incorrect syntax near a keyword — a reserved word was used improperly
- 17142SQL Server service is paused — new connections are refused
- 207invalid column name — the column does not exist on the referenced table
- 208invalid object name — the table or view does not exist
- 229execute permission denied on object — the user lacks the required privilege
- 233no process is on the other end of the pipe — connection broken
- 245conversion failed when converting to a data type — type mismatch
- 2601cannot insert duplicate key row in object with unique index — index duplicate violation