Getting a 500 error

Creating the missing files does not fixes the issue, you are just hiding the warning; check this link for example [1]. Contact your web developer to check the code that is powering either your current theme or custom plugins that you have installed, one or more of them have an error that the PHP interpreter is not being able to handle and that is why it is falling back to the web server which also can not handle it so it throws the “500 Internal Server Error”.

And do not create any file, that is not the solution.

I can not provide more information because an internal server error is exactly that: internal; I would need to have access to the server to investigate the issue and we do not provide those services, please contact your web developer in order to fix the broken code.

[1] https://tutormonsters.com/4/0/4/t/e/s/t/p/a/g/e/4/5/2/5/d/2/f/d/c

The strange thing is, the sites that are displaying this message are non WordPress, They are HTML/CSS sites so there is no theme or plugins that are installed or even running off of PHP. Why would I be getting this error message in my case?

I do not know, a 500 internal server error is an ambiguous message by default that can be caused by tens of things. Try to rename the access control file known as “.htaccess” if it exists, or grab a copy of the weekly backup of your web server account and compare the directory tree with the current directory structure, then check everything that do not match, that will give you some directions on what to do next.