A website or webmail is unavailable with the error message:
HTTP Error 503. The service is unavailable.
There are no errors in domain's error log in Plesk at Domains > example.com > Logs.
The following error message appears at Domains > example.com > Dedicated IIS Application Pool for Website:
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
The website's IIS application pool is stopped.
Start the website's application pool:
Go to Domains > example.com > Dedicated IIS Application Pool for Website.
Click Switch Off.
Click Switch On.
Via RDP connection
Connect to a Plesk server via RDP.
Start a command prompt as an Administrator and run the command:
C:> plesk repair web example.com -y