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Article ID: 124286, created on Jan 26, 2015, last review on Jul 14, 2018

  • Applies to:
  • Plesk Automation 11.5


When I access the list of databases on a Database Server ( Infrastructure -> Database Servers -> Database Server name -> Databases Tab *) I get the error:

Unknown SSL protocol error in connection to IP:8443 ' occurred during the connection to the agent at 'https://IP:8443/agent.cgi


SSLv3 protocol is disabled on the Service Node. Till the PPA MU#8 it is required for communication between Management and Service nodes.


  1. Check Plesk log at /usr/local/psa/admin/logs/panel.log, it will show an error when accessing Databases Tab:

        2014-10-25T15:07:53-05:00 DEBUG (7)  [util_exec]: Start plesk agent: transaction=4d6e77cb88ca8d35b4e178bd255d490f, transport=remote
    2014-10-25T15:07:53-05:00 ERR (3)  [panel]: The error 'Unknown SSL protocol error in connection to IP:8443 ' occurred during the connection to the agent at 'https://IP:8443/agent.cgi'.:
    0: JsonRpc.php:268
    1: JsonRpc.php:330
            Service_Agent_Transport_JsonRpc->_post(string 'https://IP:8443/agent.cgi?action=exec&transactionId=4d6e77cb88ca8d35b4e178bd255d490f', string '[{"method":"exec","params":{"id":0,"cmd":"mssqlmng","args":["--get-server-version","--server=*Database Server name*","--login=sa","--password=*PASSWORD*"],"version":"1.0","input":null,"env":[]}}]')
    2: JsonRpc.php:110
            Service_Agent_Transport_JsonRpc->_exec(string '4d6e77cb88ca8d35b4e178bd255d490f', array, object of type Service_Agent_ResponseBatch)
  2. Log in to the Service Node with MSSQL installed and check whether the SSLv3 is enabled in registry. On x64 Windows system it is located in the following path:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server
  3. Set registry value to '1' for 'Enabled' parameter.

  4. Reboot host in order to apply changes.

P.S. If you need to disable SSLv3 on your windows service node check CVE-2014-3566. POODLE attack exploiting SSL 3.0 fallback. Please note, that MU#8 should be installed before.

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