If you do face this error message “Grader ran out of memory while grading the submission. Please contact support or wait for 24 hours to submit” from the grader’s output, comment in this thread if it is still not solved after 24 hours and we will figure out a way to get it solved.
Remember to submit your assignment with the training cells commented.
Update: Also, if you are using a high number of units in the dense layer, it may cause this error so please keep them to 64 or max 128 to avoid it.