Microsoft says a "really bad" bug halted Windows 11 25H2 rollout to Canary channel

If you’ve been waiting for Windows 11 version 25H2 to show up in the Canary channel, you’re not alone. Many expected Windows 11 25H2 to land last week, sadly, but it didn’t due a bug, which Microsoft calls “really bad.”

Newer code changes in Windows 11 25H2 introdces a bad bug that nearly broke entire OS

Microsoft confirmed on the official Windows Insider Program X account that no new Canary build was coming as expected. Later, Brandon LeBlanc, Senior Program Manager on the Insider team, gave some extra context of why the rollout of Windows 11 25H2 was halted.

According to LeBlanc, the delay is due to a “really bad” bug. LeBlanc, in his tweet, notes, “We tried really hard with Canary, but this new bug is really bad. I know this is disappointing. I am currently re-imaging a PC now to validate the fix for Canary for next week’s flight though.“

Well, it’s not just some other bug. This one impacts core parts of the system, including Bluetooth, Wi-Fi, USB, even the Camera. He further added:

It’s hard to describe in a post but it impacts functionality across the OS ranging from Bluetooth and Wi-Fi to connecting USB accessories and even your onboard camera (which impacts Windows Hello on PCs too).

When users asked if the issue was already affecting public builds, LeBlanc clarified that it comes from newer code changes that haven’t been released yet. We are guessing it’s most likely related to the upcoming Windows 11 25H2 update. LeBlanc, talks about it, and mentions:

It is a specific bug that is impacting builds we have not released to Windows Insiders based on a code change we made in newer builds, so you wouldn’t be experiencing this specific bug. This issue is completely unrelated to AMD GPU/chipset drivers.

While Microsoft hasn’t officially confirmed that 25H2 testing has started, the clues are all there. And this delay might be part of that process. All that said, Microsoft is aware of the issue and is already testing a fix.