Print screen button does not work after upgrading to Ubuntu 18.04 [duplicate]

Solution 1:

The default program to take screenshots in Ubuntu is gnome-screenshot.
Run command gnome-screenshot on terminal to know if the problem is in gnome-screenshot or something else. To provide you just a workaround, you can create another shortcut by going to - System Settings -> Keyboard -> Shortcuts and press + button there. A menu like below will appear

Enter gnome-screenshot in the name and gnome-screenshot -w in command.
-w is for taking screenshot of the current window.
After entering name and command, press apply, and custom shortcut be added to your list. Click on the "Disabled", and the text should change to "New accellerator". This is where you set a new shortcut, for example - Shift + Ctrl + Alt + C.