A website or webmail does not work on a Plesk for Windows server: Error 503. The service is unavailable

Symptoms

• A website or webmail is unavailable with the error message:

  PLESK_INFO: HTTP Error 503. The service is unavailable.

• There are no errors in domain's error log at Domains > example.com > Logs.

• In some cases, the following error message appears at Domains > example.com > Dedicated IIS Application Pool for Website:

  PLESK_ERROR: Error: Your server's applications pool is not running, but it was not stopped through Plesk. There might be some issue with IIS. You can restart the application pool

Cause

The website's IIS application pool is stopped.

Resolution

Start the website application pool:

1. Log in to Plesk.

2. Go to Domains > example.com > Dedicated IIS Application Pool for Website.

3. Click Switch Off.

4. Click Switch On.

1. Connect to a Plesk server via RDP.

2. Start a command prompt as an Administrator and run the command:

   C:\> plesk repair web example.com