At first glance, it appears to be utterly useless. The only useful message seems to be “Login failed for user ‘myuser‘.” but what we really need to know is “why?”.
That information is somewhat buried in this section of the message:
Server Name: mysqlserverinstance
Error Number: 18456
Based on the documentation for this error, the severity and state actually mean something. I have copied and pasted the same from the link.
Read on to find out how to get the actual error.