When a website is opened, it asks for authentication or redirected to IIS error message:
HTTP Error 401.3 - Unauthorized
You are not authorized to view this page due to invalid authentication headers.
IIS > Sites > example.com > Authentication > Anonymous Authentication > Specific user is selected.
IWPG_ users does not have permissions to access vhost directory files.
Find proper system username for affected domain:
"%plesk_bin%"\\dbclient.exe --direct-sql --sql="select login from sys_users where home like '%example.com%';"
Grant read permissions for user 'exampleuser':
icacls "%plesk_vhosts%"\\example.com\\httpdocs /grant IWPG_exampleuser:r /T