Logging in to SQL Server after starting in single-user mode using –m, you might get the following:
Cannot connect to..
Additional information:
Login failed for user ‘DOMAIN\user’. Reason: Server is in single user mode. Only one
administrator can connect at this time. (Microsoft SQL Server, Error: 18461)

Workaround- try to stop the Reporting Services Service and/or the SQL Agent Service if running. This will ensure that only one connection is made by an administrator.
Thanks,
Lee
-----------------------------

a7cb223c-9b45-4509-b6d6-e3700194e063|0|.0