Error when saving file in Classic Paint

I have a machine running Windows 10 Pro, version 1703, build 15063-413. The File -> Save function no longer works in Classic Paint. When I try and save the file, I am greeted with the following message. I replaced my name with username.

C\Users\username\Pictures\picture.jpg
Paint cannot save this file
Save was interrupted so your file has not been saved.

The Save As function still works. Anyone else come across this issue? Is there a remedy? Thanks.

This same problem seems to have been around since Windows XP and there are a lot of suggestions out there.

This one looked interesting. It's for Windows 7, but it might help to have a look through it:

Solve Paint Cannot Save This File Problem in Windows 7