Sqlserver error 18456

If SSH2 is used and tested on its own machine, an error is reported to the teacher. Struts reports the following error:

A resourcepool cocould not acquire a resource from its primary factory or source.
Connections cocould not be acquired from the underlying database!
Hibernate operation: cannot open connection; uncategorized sqlexception for SQL [???]; SQL State [null]; error code [0]; connections cocould not be acquired from the underlying database !; Nested exception is Java. SQL. sqlexception: connections cocould not be acquired from the underlying database!

And then try to log on to management studio with your new login name. The error 18456 is returned...

I have been searching for N for a long time (mainly because the answer is not the answer to this problem, which is copied by N-plus websites ...) Finally found ~

Then it will be okay ~