A keyboard shortcut doesn't work in virtual machine

Symptoms

• I cannot use one of the following key combinations in my virtual machine (VM):

  CTRL + left/right arrow 
  CTRL +  up/down arrow
  CTRL+ SHIFT + left/right arrow 
  CTRL + SHIFT +  arrow
  

Cause

Parallels Desktop or macOS misconfiguration.

Resolution

To forward all keyboard shortcuts to the virtual machine (VM):

1. Open Parallels Desktop preferences > Shortcuts > macOS System Shortcuts:

   

Now whenever your virtual machine is in focus (mouse/keyboard control is grabbed by the VM) all Mac system shortcuts will be passed into the virtual machine, and they will work as your virtual machine's shortcuts.

Alternative solution

Ctrl+Arrow(s) keyboard combinations are assigned to Mission Control by default in macOS. You can disable these shortcuts in System Preferences > Keyboard > Shortcuts > Mission Control:

This will disable the use of shortcuts for Mission Control. However, since Mission Control supports gestures, most people with gesture-capable machines won't even need the shortcuts. Also, you could assign other shortcuts to Mission Control if you like.