Failed Logins Attempts

This warning has been raised because the server error log has found one or more failed database logins. Although they may be benign, such as DBA mistyping a password, they may also be a result of an attempt to gain unauthorized access to the database.

Suggested Action

Investigate the login failures.

How to Scan the SQL Server Error Log for Failed Logins

DECLARE @SearchText NVARCHAR(40) = 'login failed';
EXEC master.dbo.xp_readerrorlog 0, 1, @SearchText, NULL, NULL, NULL;;

Further Reading

MSSQLSERVER_18456 | Microsoft Docs