To answer your question:
- A 500 error is indicative of a PHP crash.
- We don’t have extensive mod_security rules on our hosting (too high risk of false positives). And requests that are blocked will get a clear 403 Forbidden response, not an 500 Internal Server Error.
- I’m not aware of any compatibility issues between our hosting and MyBB.
Or the issue only happens if your database credentials are incorrect, and you were just entering incorrect details even when you thought you were entering correct ones.
To fix this, I can suggest two approaches.
The first is to try stop speculating about the 500 error and instead try and get more information about it. An actual PHP error message would help a lot in figuring this out.
The second option is to skip installing MyBB manually entirely and just install it with Softaculous. Softaculous offers MyBB and can handle the installation for you.