Multimedia keys not working after updating gnome
Solution 1:
In the System Settings there is the keyboard section in hardware. Check shortcuts tab. Clicking one of the short cuts you can change the accelerator manually by typing in what you wish to use. Example from my keyboard is I changed my web browser button from the standard WWW that is mentioned to the Home Page icon (House) and it set itself that way. I am unsure why the settings didn't auto install when upgraded etc. Hope this helps. I'm pretty new and slowly learning.