[qubes-users] Qubes OS 4.2.1-rc1 is available for testing

Dear Qubes Community,

We're pleased to announce that the first [release candidate (RC)](#what-is-a-release-candidate) for Qubes OS 4.2.1 is now available for [testing](Testing new releases and updates | Qubes OS). This [patch release](#what-is-a-patch-release) aims to consolidate all the security patches, bug fixes, and other updates that have occurred since the release of Qubes 4.2.0. Our goal is to provide a secure and convenient way for users to install (or reinstall) the latest stable Qubes release with an up-to-date ISO. The ISO and associated [verification files](Verifying signatures | Qubes OS) are available on the [downloads](Download Qubes OS | Qubes OS) page. For more information about the changes included in this version, see the [full list of issues completed since the release of 4.2.0](Issues · QubesOS/qubes-issues · GitHub).

## When is the stable release?

That depends on the number of bugs discovered in this RC and their severity. As explained in our [release schedule](Version scheme | Qubes OS) documentation, our usual process after issuing a new RC is to collect bug reports, triage the bugs, and fix them. If warranted, we then issue a new RC that includes the fixes and repeat the process. We continue this iterative procedure until we're left with an RC that's good enough to be declared the stable release. No one can predict, at the outset, how many iterations will be required (and hence how many RCs will be needed before a stable release), but we tend to get a clearer picture of this as testing progresses. Here is the latest update:

At this point, we expect the stable release sometime around 2024-03-25.

## Testing Qubes 4.2.1-rc1

If you're willing to [test](Testing new releases and updates | Qubes OS) this new RC, you can help us improve the eventual stable release by [reporting any bugs you encounter](Issue tracking | Qubes OS). We encourage experienced users to join the [testing team](Joining the Testing Team). The best way to test Qubes 4.2.1-rc1 is by performing a [clean installation](Installation guide | Qubes OS) with the new ISO. We strongly recommend [making a full backup](How to back up, restore, and migrate | Qubes OS) beforehand.

As an alternative to a clean installation, there is also the option of performing an in-place upgrade without reinstalling. However, since Qubes 4.2.1 is simply Qubes 4.2.0 inclusive of all updates to date, this amounts to simply using a fully-updated 4.2.0 installation. In a sense, then, all current 4.2.0 users who are keeping up with updates are already testing 4.2.1-rc1, but this testing is only partial, since it does not cover things like the installation procedure.

## Reminder: new signing key for Qubes OS 4.2

As a reminder, we published the following special announcement in [Qubes Canary 032](Qubes Canary 032 | Qubes OS) on 2022-09-14:

We plan to create a new Release Signing Key (RSK) for Qubes OS 4.2. Normally, we have only one RSK for each major release. However, for the 4.2 release, we will be using Qubes Builder version 2, which is a complete rewrite of the Qubes Builder. Out of an abundance of caution, we would like to isolate the build processes of the current stable 4.1 release and the upcoming 4.2 release from each other at the cryptographic level in order to minimize the risk of a vulnerability in one affecting the other. We are including this notice as a canary special announcement since introducing a new RSK for a minor release is an exception to our usual RSK management policy.

As always, we encourage you to [authenticate](Qubes security pack (qubes-secpack) | Qubes OS) this canary by [verifying its PGP signatures](Verifying signatures | Qubes OS). Specific instructions are also included in the [canary announcement](Qubes Canary 032 | Qubes OS).

As with all Qubes signing keys, we also encourage you to [authenticate](Verifying signatures | Qubes OS) the new Qubes OS Release 4.2 Signing Key, which is available in the [Qubes Security Pack (qubes-secpack)](Qubes security pack (qubes-secpack) | Qubes OS) as well as on the [downloads](Download Qubes OS | Qubes OS) page under the Qubes OS 4.2.0-rc5 ISO.

## What is a release candidate?

A release candidate (RC) is a software build that has the potential to become a stable release, unless significant bugs are discovered in testing. RCs are intended for more advanced (or adventurous!) users who are comfortable testing early versions of software that are potentially buggier than stable releases. You can read more about Qubes OS [supported releases](Supported releases | Qubes OS) and the [version scheme](Version scheme | Qubes OS) in our documentation.

## What is a patch release?

The Qubes OS Project uses the [semantic versioning](https://semver.org/) standard. Version numbers are written as `<major>.<minor>.<patch>`. Hence, we refer to releases that increment the third number as "patch releases." A patch release does not designate a separate, new major or minor release of Qubes OS. Rather, it designates its respective major or minor release (in this case, 4.2) inclusive of all updates up to a certain point. (See [supported releases](Supported releases | Qubes OS) for a comprehensive list of major and minor releases.) Installing the initial Qubes 4.2.0 release and fully [updating](How to update | Qubes OS) it results in essentially the same system as installing Qubes 4.2.1. You can learn more about how Qubes release versioning works in the [version scheme](Version scheme | Qubes OS) documentation.

This announcement is also available on the Qubes website: