DLS Course 4: When Saving: "Permission denied: W4A1/Face_Recognition.ipynb"

Sorry about this trouble. The course staff has reported to Coursera and are waiting to hear back.

In general, the better idea is to save the notebook in its original form as an “ipynb” file. You have that option under “File → Download as notebook (ipynb)”. Then you can just upload it again instead of having to copy and paste. There is more information about how to save all files associated with the assignments on the DLS FAQ Thread.