I was working on production environment and this error was appearing each couple of minutes and i go mad as we uninstall some windows updates, disable teaming on the SharePoint and SQL servers but the error appears the next day
Event ID: 27745
The description for Event ID 27745 from source Windows SharePoint Services 3 cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.
If the event originated on another computer, the display information had to be saved with the event.
The following information was included with the event:
#50071: Unable to connect to the database xxx sql database. Check the database connection information and make sure that the database server is running.
After digging more and more I found these errors in the SQL servers’ logs:
The SQL Server Network Interface library could not register the Service Principal Name (SPN) for the SQL Server service. Error: 0x2098, state: 15. Failure to register an SPN may cause integrated authentication to fall back to NTLM instead of Kerberos. This is an informational message. Further action is only required if Kerberos authentication is required by authentication policies.
Error: 17806, Severity: 20, State: 2.
SSPI handshake failed with error code 0x80090304 while establishing a connection with integrated security; the connection has been closed. [CLIENT: IP]
Error: 18452, Severity: 14, State: 1.
Login failed. The login is from an untrusted domain and cannot be used with Windows authentication. [CLIENT: IP]
The resolution was setting SPN for the SQL server
setspn -A MSSQLSvc/FQDN:1433 accountname
setspn -A MSSQLSvc/FQDN accountname