> In what situation do you mean by the back button?
I mean the student was doing a TaskChain task, finished the task, hit the back button on the browser, and then redid the task and finished the task again. At the point, they will be told that that the attempt has already finished.
Another situation that this message can appear is when a student starts a task attempt in one browser window, then starts another attempt at the same task in another window. When they start the attempt in the second window, the server marks the attempt in the first window as abandoned, but the student only discovers this when they try to submit results from the first window. The results for the second window should be received without a problem.
There may be other cases. If you can isolate the conditions, I would be glad to hear them.