Non-Qubes-Whonix ™: No preparation is required.
Qubes-Whonix ™: A Qubes VM kernel is required.
- Follow the Qubes OS Installing kernel in Debian VM [archive] instructions.
- Ensure the Qubes VM kernel is functional before proceeding -- Qubes VM kernel issues should be raised at Qubes support [archive] and not in Whonix ™ forums.  
- Reboot dom0 with Qubes VM kernel. This is because Qubes VM kernel might break unrelated things such as the USB VM. 
- Once the Qubes VM kernel is functional, proceed with the following instructions.
- https://forums.whonix.org/t/what-to-post-in-this-qubes-whonix-forum-and-what-not/2275 [archive]
- Qubes feature request: Simplify and promote using in-vm kernel [archive]
- As experienced firsthand by Whonix ™ developer Patrick Schleizer.
- Users should Prefer Packages from Debian Stable Repository, but using backports is better than manual software installation or using third party package managers since this prefers APT. To contain the risk, Non-Qubes-Whonix ™ users might want to consider using Multiple Whonix-Workstation ™ and Qubes-Whonix ™ users might want to consider using Multiple Qubes-Whonix ™ TemplateVMs or Software Installation in a TemplateBasedVM.
- Most often this step applies before attempting major Whonix upgrades; upgrade instructions are also made available at that time (see Stay Tuned).
This is a wiki. Want to improve this page? Help is welcome and volunteer contributions are happily considered! Read, understand and agree to Conditions for Contributions to Whonix ™, then Edit! Edits are held for moderation.
Copyright (C) 2012 - 2019 ENCRYPTED SUPPORT LP. Whonix ™ is a trademark. Whonix ™ is a licensee [archive] of the Open Invention Network [archive]. Unless otherwise noted, the content of this page is copyrighted and licensed under the same Freedom Software license as Whonix ™ itself. (Why?)