There was a problem grading your submission. Check stderr for more details.
How do i correct this
Hello @sudhishna_sudevan !
I hope your day is going well 
please provide us with more details about the error you are facing so we can help you.
I have the similar issue - all tests passed for all the functions in the assignment notebook but during assessment it fails to asses Test_get_country and Test get accuracy with the similar error message: There was a problem grading your submission. Check stderr for more details.
I found the issue explained in the separate topic: C1_W3_Assignment from nlp course
Issue solved, thanks