Launching a course in Learn errors out for only one course

Summary

Launching a course in Learn shows - We're sorry, the page you are looking for cannot be found.

Content

We are testing the 19D upgrade in staging for TEE and when user started testing Learn they encoutered an error message for one particular course the error is as follows 'We're sorry, the page you are looking for cannot be found.' 

Reached out to Oracle and they mentioned that this error is no relation with 19D upgrade. They have given steps to resolve this issue. Below is the preferred and alternate solution provide. We are yet to apply this, but wanted to know is there a way to check what is causing this issue?  Did anyone else have encountered this in the past and found out what was the root cause and how did they resolve it.