Logon failed for login due to trigger execution
According to the screenshots you posted you are encountering an Error 17892 which translate roughly to a logon trigger error.

You might have previously had a logon trigger that evaluated if you were allowed to log in to the SQL Server or not. This trigger may have been removed or might produce wrong results which now does not allow anybody to log in to the SQL Server instance.

There are three possible workarounds:

1. Open Query Window Available

Search for the trigger via:

SELECT * FROM sys.server_triggers;


If you see a server level trigger that might be responsible for the login issues, then you can drop it with:

DROP TRIGGER triggername ON ALL SERVER;


Instead of dropping the trigger just disable it with:

DISABLE TRIGGER triggername ON ALL SERVER;


2. DAC Allowed; No Open Query Window Available

If you don't have an open Query Window, then you will have to log in to your SQL Server instance with a DAC (ADMIN) connection:

sqlcmd –S 127.0.0.1,1434 


1434 is the default port for the DAC connection

You can then run the above queries from solution 1. to determine the trigger and then drop or disable the trigger.

3. No Open Query Window; No DAC Allowed

If you don't have an open Window and DAC has not been turned on, then you are going to have to stop the instance and start again using the following steps:

sqlserver.exe –c -m –f


This will allow you to start the instance in single user mode with minimal configuration and shorter startup time.

Then you can disable the triggers according to step 1. above.