Howard Miller

Switch on Debugging to get the full trace.

Firstly, DO NOT use the database for session storage. It doesn't work very well and kill your database. Get yourself Redis.

Secondly, is this condition after a long delay? In which case, it's just a symptom of something else timing out.

So why do your images show a different URL?

Ok - you say you are using localhost but your images show https://moodle-project.ddev.site (which is not localhost)

The error message says that the certificate for this site is invalid. You say this is not the problem but have not demonstrated how you know this to be the case. You have already had tools suggested for check certificate validity.

If you can't / won't make the tests (and provide results thereof) that have been suggested to you in good faith then I don't see how we can help further.

Again "if it quacks like a duck" and so on. Error messages like that are normally true

Sorry - I don't know what you mean by the "length of a course". Which bit are you having problems with?