If you are getting the error "Executing in an invalid environment for the supplied user " while loading website in cPanel Server.Please check whether the domain is redirected to domain/cgi-sys/suspendedpage.cgi url.
For example :
Domain :
https://makkellen.tk/Redirected to :
https://makkellen.tk/cgi-sys/suspendedpage.cgijust confirm that your domain suspended. Execute below command
/scripts/unsuspendacct <User Name>
Reason for getting this error :
1.Account suspended and file suspendedpage.cgi not execute properly.
2.Happened when the hosted site is using third party DNS and pointing to wrong IP (a working IP on your server but not the one where domain is hosted). You will need to either point the the domain to correct IP or change the IP in WHM to match the DNS.
Reference :
http://cpanelplesk.com/executing-in-an-invalid-environment-for-the-supplied-user/All The Best