If you are joining a session via an email or a link on a website (not via Blackboard) you may see a Not Found error
This is down to a bug in Blackboard which will show you this if you’re logged in to Blackboard, but not enrolled on the course where the session was created (i.e. the very reason why you were sent a guest link in the first place).
Until this bug is fixed, you’ll either need to log out of Blackboard, or open the link in another browser where you’re not logged into Blackboard.
Note This does not affect joining Collaborate sessions via the Collaborate tool in your modules on Blackboard.