Website is not working: Server Error in '/' Application

Symptoms

Website shows the following error in a browser:

Server Error in '/' Application.
Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: An error occurred loading a configuration file: Failed to start monitoring changes to 'C:\\Inetpub\\vhosts\\example.com\\httpdocs' because access is denied.

Source Error:

[No relevant source lines]

Source File: C:\\Inetpub\\vhosts\\example.com\\httpdocs\\web.config    Line: 0

OR

Server Error in '/' Application.
Failed to start monitoring changes to 'C:\\Inetpub\\vhosts\\example.com\\bin' because access is denied.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Cause

Incorrect virtual hosts' security settings.

Resolution

1. To fix security settings for all subscriptions, run:

   Plesk Reconfigurator > Repair Plesk installation > Plesk Virtual Hosts Security > Check

2. To fix security settings for only one subscription, run via command line:

   cd "%plesk_cli%"
   repair.exe --repair-webspace-security -webspace-name example.com