Upgrading from Windows Parallels Plesk 8.1.1 to 8.6 went smoothly according to the installer, however, after the upgrade completed and machine rebooted the Plesk control panel no longer loaded.

It would often return an error to the browser, but, also occasionally would say:

get_config_string failed: PRODUCT_DATA_D: The system cannot find the file specified. (Error code 2) at Unable to connect to pipe \\.\pipe\psapipe

Tried running the Plesk reconfigure tool to fix the problem, however, it didn’t help.  Contacted Parallels Plesk support and they started looking into it after some time.

It turns out that….

I am working on this issue currently. I’ve found out that Plesk database was not upgraded to appropriate version at all. It is still from 8.1.0 version:

C:\Program Files\SWsoft\Plesk\admin\bin>dbclient.exe –direct-sql –sql=”select * from upgrade_history”
upgrade_date    version_info    db_version
2007-02-16 00:00:00     8.1.0   7.5.6

As there is not automatic toll for upgrading database I am upgrading it manually. It will take some prolonged time. Please, wait, I will keep you updated with any news.