Unable to choose language in Plesk. Only English is available

Symptoms

• One only English language is available in Plesk interface in spite of purchased additional language pack.

• The following can be found in C:\ParallelsInstaller\autoinstaller3.log

  CONFIG_TEXT: [2020-05-07 21:03:30.276281] Registering locales...
  [2020-05-07 21:03:30.824719] Package action: Execute, package: plesk-l10n, exec time: 0 sec. desc: "program='[PLESK_INSTALLDIR]\admin\engine\php.exe'," "command-line='C:\Program Files (x86)\Plesk\admin\plib\scripts\add-locales.php'," "working-dir=''," "context=''," "arch=''", output='~empty'
  [2020-05-07 21:03:30.824719] C:\Program Files (x86)\Plesk\admin\engine\php.exe "C:\Program Files (x86)\Plesk\admin\plib\scripts\add-locales.php" failed with error 255(0x000000ff). Output:
  Sub-action 'Execute' failed with error code: 255(0x000000ff)

Cause

Installed locales are not properly registered.

Resolution

1. Connect to the server via RDP

2. Launch locale installer in command line to register these:

   C:\> plesk php "C:\Program Files (x86)\Plesk\admin\plib\scripts\add-locales.php"