Plesk 12.x / Linux :: Prompt For Password When User Clicks On Database In Account

We use CentOS Linux 7.0.1406 (Core) with Plesk Version 12.0.18 Update #27.

We have the following problem:

When a user clicks on a database in his account and tries to login with phpmyadmin, Plesk prompts for a Password of that specific user. The message is (in german):

Code:

The site https://........:8443 responded with:
Enter the password to log in as the database user xxxxxx

When i enter the correct password a new phpmyadmin window opens and the user can use his database. A few days ago you didnt have to enter a password at all. When you were logged into Plesk as a user, you could just click "Databases -> Webadmin" and phpmyadmin opened up without Plesk asking for a password.

The question for the password is NOT coming from phpmyadmin. Its from Plesk itself. After i enter the correct password plesk hands the request over to PMA.

For debugging i created a new database for a user and i could enter its database without any problem. No password was required. But the existing old databases now all require a password. So obviously Plesk is not aware of these passwords anymore. I guess they are/were stored somewhere.