Article ID: 121386, created on Apr 29, 2014, last review on Jun 15, 2016

  • Applies to:
  • Plesk 11.5 for Windows


After the failed upgrade attempt, Plesk utilities fail with the following error:

PleskMainDBException: The server requested authentication method unknown to the client
file: E:\Parallels\Plesk\admin\plib\db.php
line: 451
code: 0
trace: #0 E:\Parallels\Plesk\admin\plib\db.php(411): reconnect()
#1 E:\Parallels\Plesk\admin\plib\auth.php(137): db_connect()
#2 {main}

The dbclient.exe utility fails to execute SQL queries with the following error:

Failed to connect to database: Can't connect twice. Already connected
   at (MySQLDatabaseProvider::connect line 199)


There are two entries for admin user in Plesk database. One with '%' in the 'host' field, the second one with 'localhost':

mysql> select user,host from user where user='admin';
| user  | host      |
| admin | localhost |
| admin |     %     |


  1. Create psa backup according to:

    881 How to backup/restore a Plesk database dump?

  2. Access psa database according to:

    3472 How to access Plesk database?

  3. Remove the entry with '%' value in 'host' field:

    mysql> delete from user where host=%;

Search Words

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