When the panel (or a website) is reachable at his URL but a page (even the main page) cause an error or a blank page, the first thing to do is to track the logs !
Note : replace below domain.tld by your domain (or subdomain) full name.
The logs for the panel itself are in
/var/logs/apache2/error.log or /var/logs/httpd/error.log
The logs for the domain domain.tld are located in directory
/var/zpanel/logs/domains/[your-Sentora-login]/domain_tld (ubuntu, CentOS)
(see also Sentora important files paths)
Ubuntu & CentOS:
In an SSH console or local console enter:
tail -f /var/log/apache2/error.log
tail -f /var/zpanel/logs/domains/[your-Sentora-login]/domain.tld-error.log
The console displays the 10 last lines and will display automatically each new line writen in the file.
=> While it is waiting, do an access to the page that fails and note the new error that is displayed.
To stop tracking and go back to prompt, press CTRL-C
The "tail" tool is not provided natively for windows, but you can find some equivalent by a search for "tail for windows". Some equivalent returned :