Unable to take full screen screenshots "Your screenshot can't be saved" I'm currently on Catalina 10.15.4 and recently started seeing a popup whenever I try to take full screen screenshots. A window pops up saying "Your screenshot can't be saved. Unable to capture window image." I've tried to capture via the grab tool and also pressing ⌘ Command ⇧ Shift 4 then Space then and then clicking. 

I've tried changing the default directory that my screenshots are saved to from the desktop to a folder called screenshots but this didn't help.
defaults write com.apple.screencapture location ~/Screnshots.

Any ideas why this might be happening?
Does your Mac have a Touch Bar? If so, check the location shown there after you press Cmd + Shift + 4. Is it a valid folder?