When something is not right, and our website is not opening, it will log all the errors happening in a log that can be accessed through our File Manager, and if there is any error it will be listed on error_log.
You can open the file and run your diagnostic according to the message:
Another way is showing the error on the webpage when you try to open the URL that is not working.
To do this, we need to enable the display_error on PHP settings.
- Open Plesk
- Websites & Domain
- Look for display_errors
And leave it ON.
Once you have checked the error and solved the issue, the ideal is to let it off, once it can happen that the website shows also warnings related to PHP code that don't affect the website but will show as error message even with your website running.