I was solving the exercise by saving the progress manually to a file locally. Then, when I reloaded the exercise and pasted the code I had developed, the program stopped responding.
Solution: use the save button or rewrite the previous code.
In my case it didn’t matter if it was exactly the same tabulation.
good to know that you have solved the problem. Python is very picky with tabulations and empty spaces, and for now we have no support for Python debugging in Unibotics. So in case of some syntax errors in the source code from the user, they may break the exercise.py that runs inside the backend. That break makes the GUI frequency drops to 0 and the stop of the whole program…
Adding Python debugging support to Unibotics is in the roadmap, but in the midterm. So for now just be careful about the tabulations and empty spaces. The saving button works fine, anyway.