Error Message:
2016-06-27 14:27:41,741 - Checking trust login for gpmon on db gpperfmon, host localhost, port :5432 2016-06-27 14:27:41,750 - Trust login not allowed. User gpmon has trust login enabled 2016-06-27 14:27:41,751 - Authentication failed user(gpmon) allow_trust_logon(False): Incorrect username/password
The gpperfmonui.conf parameter allow_trust_logon is set to "no" and the user (or all users) is a trusted user. This means that it refuses to let you log on as you are trying as a trusted user.
On checking the pg_hba.conf file, you should see that you as a user or all users are trusted:
host all all 127.0.0.1/28 trust <user> all all 127.0.0.1/28 trust
Follow the steps to resolve this issue: