WordPress website in Plesk shows 500 Internal Server Error on Windows: open_basedir restriction in effect: .mo is not within the allowed path(s)

Symptoms

• Website on WordPress is unavailable:

  PLESK_INFO: 500 Internal server error

• Accessing this website from the server returns the following error message:

  PLESK_INFO: PHP Warning: is_readable(): open_basedir restriction in effect. File(C:inetpubvhostsexample.comhttpdocs/wp-content/plugins/C:/inetpub/vhosts/example.com/httpdocs/wp-content/themes/sometheme/plugins/tf-flexslider/lang/en_US.mo) is not within the allowed path(s): (C:/inetpub/vhosts//example.com;C:WindowsTemp) in C:inetpubvhostsexample.comhttpdocswp-includesl10n.php on line 457

  ---

  The website may be accessible but an attempt to install a plugin at Plesk > WordPress > example.com > Plugins fails with the same error above.

Cause

The absolute path to the WordPress theme localization .mo file is concatenated with the path to the plugin directory and, as a result, restricted by open_basedir PHP parameter.

Resolution

Note: the resolution contains a common suggestion on addressing such issues. The case may be different for different themes and plugins. For the exact specific solution, refer to plugin support page or contact plugin developers.

1. Log into Plesk.

2. Access file manager in Domains > example.com > File Manager.

3. Edit the file, mentioned in the error, e.g. httpdocswp-includesl10n.php.

4. Find WP_PLUGIN_DIR and replace it with basename( dirname( __FILE__ ) ).

   For example, replace:

   $path = WP_PLUGIN_DIR . '/' . trim( $plugin_rel_path, '/' );

   With:

   $path = basename( dirname( __FILE__ ) );

5. Save changes.

Additional information

Domain does not work: open_basedir restriction in effect