Apple's high-end Mac Studio with M3 Ultra Apple Silicon will download macOS Tahoe, but it won't install, leaving users stuck on the older system version.
When Apple rolled out macOS Tahoe worldwide on September 15, 2025, most devices updated without a hitch. MacBooks, iPads, and even older Intel machines took the upgrade in stride.
The story has been very different for the Mac Studio with M3 Ultra. Owners of Apple's $4,000 desktop powerhouse, inside Apple's community forums, are finding that the update looks like it's working until the very last minute.
Instead of finishing, the install is aborted when the Apple Neural Engine driver fails a hardware validation check. The system then drops back into macOS Sequoia 15.7 with no upgrade applied.
For some reason the operating system refuses to install when the Neural Engine doesn't pass validation.
What's going wrong
Community reports point to the Apple Neural Engine, the dedicated block of silicon that accelerates AI and media tasks. Logs show that during the install, Tahoe tries to validate a hardware register linked to the Neural Engine but fails.
The mismatch stops the upgrade in its tracks. The kicker is that only the M3 Ultra appears to choke. MacBook Pro models with M3 and M3 Max chips finish the update cleanly.
Even Intel-era Macs handle the install, which rules out a universal bug.
People have tried every standard fix, according to MacRumors. They've run the installer from Terminal, downloaded the full image, booted into Safe Mode, reinstalled from Recovery, and even attempted clean installs on external SSDs.
Every method ends the same way, with the computer stubbornly returning to macOS Sequoia. Some believe the wrong build is being pushed to the Mac Studio.
Reports suggest that while a MacBook Pro on the same network fetched build 25A354, the Mac Studio kept getting the older 25A353 release. That could explain the Neural Engine crash, but Apple hasn't said anything publicly.
Others noted that Apple sometimes swaps in patched builds without changing the version number. If that's what's happening, Mac Studio owners may just have to wait until the fixed build quietly appears on Apple's servers.
Apple knows about the bug and is investigating. Support staff in Europe confirmed engineers are reviewing logs and working on a fix. No timeline has been promised.
Apple knows about the bug and is investigating.Feedback Assistant also shows few public reports, which isn't unusual during the first week of a release. Apple typically rolls bug fixes into the first point release, which in this case would be macOS 26.0.1.
Why only the M3 Ultra
The fact that the bug only affects the M3 Ultra makes sense technically. The Ultra combines two M3 Max dies using a custom interconnect, which adds complexity not present in other Apple Silicon chips. That design has tripped up macOS before.
When the M1 Ultra launched, some early versions of macOS Monterey produced kernel panics under specific workloads. Apple eventually smoothed those out, but it took weeks. The same pattern seems to be playing out here.
For now, Mac Studio owners can only keep using macOS Sequoia. That means missing out on Tahoe's refreshed interface and its deeper Apple Intelligence features. Functionally, macOS Sequoia is still solid, but the optics aren't good.
