Advanced monitoring extension error: {"message":"Invalid username or password"}

Symptoms

• Advanced Monitoring page produces the following error message:

  PLESK_ERROR: error: {"message":"Invalid username or password"}

• Error as on the screenshot below occurs at any tab of Advanced Monitoring:
  
  

• The following can be found in /var/log/grafana/grafana.log:

  CONFIG_TEXT: t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:01-0700 lvl=eror msg="Invalid username or password" logger=context error="Invalid Username or Password"
  t=2020-03-09T07:20:03-0700 lvl=eror msg="Invalid username or password" logger=context error="Too many consecutive incorrect login attempts for user. Login for user temporarily blocked"

Cause

Not clear.

Resolution

1. Log into Plesk.
2. Re-enable Advanced Monitoring extension.
3. Restart Grafana service at Tools & Settings > Services Management
4. Reload Grafana extension at Extensions > My Extensions >Grafana > Open > Reload Status: