Hi, Amit.
Whenever the Lab/Jupyter won’t work or the answers is not submitting kindly restart your server or reload the page to get connected again.
Please refer to this discussions on how to restart your cloudxLab server :- I'm having problem with Assessment Engine. How should I fix?
If still you are getting the error kindly send me the screenshots. I will be happy to look into it.
All the best!
Thank you for fast help