Q: I can't open Itunes U course manager with firefox 46. What can I do

It works on Firefox here ...

Delete Firefox cookies.

https://support.mozilla.org/en-US/kb/delete-cookies-remove-info-websites-stored

Then quit and relaunch Firefox and try again.

If that didn't help, make sure Firefox is up to date.

From the Firefox menu bar click Firefox > About Firefox

If there's an update available, you'll see it in the About Firefox window.

Bookmark this URL and use it instead of a Google search:

https://itunesu.itunes.apple.com/coursemanager/