Today, Microsoft is releasing Windows 11 Insider Preview build 22449 to the Dev channel. That means that those Insiders are no longer getting cumulative updates for the RTM build of Windows 11. It also means that once you install this build, you'll have to do a clean installation of Windows if you want to roll back.

Microsoft has been warning that this will happen for a while. If you were one of those people that just wanted to test out Windows 11, the Beta channel is more your speed. Because once the OS ships, Beta channel Insiders can just switch over to production. In fact, everyone should be on Beta right now. You can always switch back to Dev if there's something you want, but you can't easily go to Beta now.

And with Windows 11 build 22449, there isn't even much that's new. The only listed change is behavior for SMB compression. Here's the full changelog:

SMB compression behavior change

We first introduced SMB compression in Windows Server 2022 & Windows 11. SMB compression allows an administrator, user, or application to request compression of files as they transfer over the network. This removes the need to first deflate a file manually with an application, copy it, then inflate on the destination PC. Compressed files will consume less network bandwidth and take less time to transfer, at the cost of slightly increased CPU usage during transfers.

Based on testing and analysis, we have changed the default behavior of compression. Previously, the SMB compression decision algorithm would attempt to compress the first 524,288,000 bytes (500MiB) of a file during transfer and track that at least 104,857,600 bytes (100MiB) compressed within that 500-MB range. If fewer than 100 MiB were compressible, SMB compression stopped trying to compress the rest of the file. If at least 100 MiB compressed, SMB compression attempted to compress the rest of the file. This meant that very large files with compressible data – for instance, a multi-gigabyte virtual machine disk – were likely to compress but a relatively small file – even a very compressible one – would not compress.

Starting in Build 22449, we will no longer use this decision algorithm by default. Instead, if compression is requested, we will always attempt to compress. If you wish to modify this new behavior to return to a decision algorithm, please see this article: Understanding and controlling compression behaviors.

Please use the Feedback Hub to give feedback or report issues with SMB compression, using the Files, Folders, and Online Storage > File Sharing category.

There are some more minor changes as well, such as a ring animation when booting instead of the circle of dots. Right-clicking on Bluetooth in Quick Settings will now open the main Bluetooth settings page, and the Windows startup sound won't play anymore after an update that installs when you're away from your PC. That's right; when Windows installs an update in the middle of the night, it won't wake you up with the boot sound.

Notifications use transparent acrylic now, and there's now a link to Touch Keyboard personalization settings in Settings. Of course, there are a bunch of fixes and known issues in Windows 11 build 22449 too.

And of course, there are a bunch of things that are still broken.

As always, you can grab the new build via Windows Update. You'll need to be on the Dev channel to get Windows 11 build 22449, which is from the rs_prerelease branch, and you can go to the Windows Insider Program page in Settings to get started.