Feature request: custom 404 error text

[mrash2]

It would be great if we could easily customize 404 error messaging with HTML so that we can point end users to documentation should they encounter a problem. For example, when BOOL_LTI_RESTRICT_LOGINS_TO_LAUNCHES = true, and the user attempts to launch via LTI but has third-party tracking blocked in their local browser, a 404 appears. We'd like to add some instructional text and a link to a knowledge base article with instructions for the user to adjust this setting themselves.

[clpetersonucf]

Customization options like this will hopefully be addressed as part of #1628.

The way you describe this issue, there may be some underlying problems associated with CORS, cookies, or headers that might need to be looked at as well. Breaking down the steps to reproduce in more detail might be helpful.

[mrash2]

Thanks, Corey!

Here's how we're getting the 404 page in this instance:

1. User's browser is set to block third-party cookies/cross-site tracking. This is the default setting in most browsers, so many users don't even realize it.
2. Materia is configured to BOOL_LTI_RESTRICT_LOGINS_TO_LAUNCHES = true to limit logins via LTI only.
3. User launches Materia from a Canvas course via LTI.
4. The Materia splash page appears within Canvas, where user selects Go to Materia.
5. The 404 message appears in a new tab or window. The only resolution for the user is to allow third-party cookies/cross-site tracking in the local browser.

We don't have the option to allow the login page because we're using LTI to provision accounts. So, while we'd rather folks encounter the 404 than the login page when this happens so that they're not aimlessly trying to lookup their username or reset their password, we'd like to be able to include some instructional text on that page. Otherwise, it feels to the user like the app is broken right from the start.

If not custom text, perhaps there's a way to trigger a specific kind of error page in this situation with some information about the cross-site tracking.

My understanding is the cross-site tracking issue is at least partly addressed with LTI 1.3 but I'm sure that's a massive undertaking of its own. Appreciate y'all!