When clicking on a specific assignment, the message " Error Retrieval for the External Use of the assignment" comes up. Why is this popping up, and how does the student access the assignment.
This sounds like an error related to an assignment that is linked to an external resource such as something from a textbook publisher. If that is the case there could be a problem with how the configuration is set up on your Canvas instance. Usually for issues like this you might get better support from the external vendor as to what the problem actually is and how to fix it.
Retrieving data ...