GMS2 has a separate "Beta" installer for people who want bug fixes or new features sooner and in exchange are willing to risk encountering bugs or issues associated with a version that has not completed testing.
It's a separate installation on your PC/Mac and so does not require you to modify your current known-good GMS2 setup, which means you can have the current stable installed and the Beta for the next major release.
However, Betas may contain bugs which could corrupt your projects and may also introduce legitimate project format changes which stop you opening the project again in other versions. Accordingly, we would therefore strongly suggest that you backup all projects before trying them on a beta.
We also ask if you use the Beta that you do report issues as soon as you see them, so that by the time the "Stable" release is made these issues have all been fixed.
Downloading The Beta Installer
You can find the installer on your YoYo Account downloads page, which is here (log-in if asked):
We release a series of betas in the lead-up to each major release and your Beta install will notify each time a new update is available, so you typically only need to get the installer from here once.
Steam users: The Beta install is not available on Steam. However, your purchase is still valid for the non-Steam version as well. If you haven't done so already, follow Using Your YoYo Account With Steam and then you can carry on with installing the Beta.
Release Notes: The links in the Help menu inside GMS2 will show you the Beta pages, but also they are here:
Review Your SDKs For The New Install
As you have just changed to a different version of GMS2 and runtimes, it's now essential that you review your external tools are suitable for use in that version, otherwise you may have issues building your projects.
See our Required SDKs FAQ and the setup guides it links to for all target platforms relevant to you.
Please don't use newer versions than what we say on that FAQ, as it might cause your builds to fail.
Current Beta Release Thread
To see the initial known issues and for giving feedback or asking questions about the new Beta version, please see the following thread on the GameMaker Community:
Submitting Bug Reports
Assuming your issue is not already mentioned in the release thread above, the process for filing bug reports is no different to the regular release. Please use the contact form linked-to inside GMS2:
Make sure you check the known issues table and the list of FAQs on the contact form before clicking that you still need to submit your bug report - you may not need to send us anything!
Also ensure that you pick the correct version number and include any logs or sample projects as requested - please assume that we will request your logs and a small sample project which just shows the issue and do include these when filing the issue, as we will want to get your issue fixed asap.
Please also be aware we need a .yyz export of your sample project, not simply the .yyp "project structure" file on its own. Use File > Export (Windows) or GameMaker Studio 2 > Export (Mac) to generate a .yyz before making your ticket.
Managing Account Sessions
Be aware that the Beta install counts as a session just the same as the regular version, so particularly if you're a school user please remember than running the Beta and the normal version at the same time would count as 2 sessions, so if you have lots of users taking part just make sure you stay within your limit, otherwise you will see the "too many sessions" message when trying to log in further users.