I'm using version 2.79 and can't redo with shift+ctrl+Z. My redo shortcut is shift+ctrl+Z and it is enabled in the Input tab in the User Preferences window. I can undo with ctrl+Z. I can redo with Tool Shelf -> Tools -> History -> Redo. Why is my shortcut not working?
This is very frustrating issue.
To solve it just use right Ctrl button on keyboard.
For whatever reason when you want to redo left one doesn't react but otherwise it works fine when you undo or do anything else, I don't understand what is the actual problem but this solution works it still beats going to Edit>redo every time.