Unable to open File Sharing: Internal error: Forbidden

Applicable to:

Opening File Sharing in Plesk > Subscriptions > example.com > File Sharing produces the following error message:

PLESK_ERROR: Internal error: Forbidden
The following error may be seen in /var/log/plesk/panel.log:

CONFIG_TEXT: ERR [panel] File sharing list retrieval failed: sharing type=private, code=403, error=Forbidden
Domain example.com is set as Web Folder root URL in Plesk > Tools & Settings > File Sharing
WordPress is installed on example.com
WordPress instance has Block access to potentially sensitive files enabled in Security Status

Product issue:

#EXTWPTOOLK-2279 " “Block access to potentially sensitive files” security measure no longer prevents File Sharing feature in Plesk from working. "
Fixed in:
- WordPress Toolkit 3.6.0 21 February 2019

Please consider updating your server:

If update is not possible for some reason you may try the following

temporary solution

Use one of the following workarounds:

Disable Block access to potentially sensitive files option in Security Status
Create a new domain like filesharing.local and set it as Web Folder root URL in Plesk > Tools & Settings > File Sharing