SQL Single User Mode Logon Failed

Ran into an issue today with one of our SQL instances where we needed to bring it up in Single User mode to recover the sysadmin role, however every time we tried to login we got the fateful “Only one administrator can connect at this time. (Microsoft SQL Server, Error: 18461)” error.

Found this great page on MSDN which you should pay close attention to if you are in a clustered environment as we are:


The important thing to note is that the cluster resource .dll will allows get the first and only connection before you have a hope in hell of getting it. The way around this is to start the MSSQL$INSTANCENAME using the net start command manually on one of the nodes and not using the Failover Cluster Manager.

This will allow you to use sqlcmd to generate the login you need to regain access.

Enjoy 😉


Richard works as a Cloud Consultant for Fordway Solution where his primary focus is to help customers understand, adopt and develop with Microsoft Azure, Office 365 and System Center. Richard Green is an IT Pro with over 15 years' of experience in all things Microsoft including System Center and Office 365. He has previously worked as a System Center consultant and as an internal solutions architect across many verticals. Outside of work, he loves motorbikes and is part of the orange army, marshaling for NGRRC, British Superbikes and MotoGP. He is also an Assistant Cub Scout Leader.