If you are using Anaconda on windows then you can open Anaconda Navigator app and go to Environment section and search for pillow in installed libraries and mark it for upgrade to latest version by right clicking on the checkbox.
This has fixed the following error:
PermissionError: [WinError 5] Access is denied: 'e:\\work\\anaconda\\lib\\site-packages\\pil\\_imaging.cp36-win_amd64.pyd'