Windows 10 Build 17666 Fails To Install For Some Insiders

Windows 10 build 17666 is by far the most interesting Redstone 5 build version Microsoft has released so far. Insiders’ feedback has been overwhelming, so if you haven’t installed this OS version yet, do hit the ‘Check for updates‘ button as soon as possible.

Unfortunately, not all Insiders have been able to download and install Redstone 5 build 17666 on their computers. As a quick reminder, Microsoft already informed Fast Ring Insiders that this build version might sometimes take longer to install. If your PC appears stuck at “Preparing to install…” somewhere between the 80%-100% in Windows Update, don’t reboot your machine. Be patient, the update will eventually install in about 30 minutes — or in some cases – longer than 30 minutes.

Wow, feature-wise this looks like the best build in a very long time. RS5 is shaping up very well, could become one of the most compelling Windows 10 updates so far (at least for me). Keep it up!

Recent reports also confirm that build 17666 sometimes fails to install altogether, reverting back to the previous OS version.

If you’re experiencing the same issue, try to install build 17666 with your antivirus disabled. If the problem persists, check out this troubleshooting guide for additional solutions.

Both updates go into the updating process, then crashes and reverts back at 75%. I’ve tried 17661 6 times and 17666 just once.

Surprisingly, Insiders haven’t reported any other bugs apart from those annoying install issues. Overall, this build is more stable and reliable than the previous builds. For more information about the list of known issues affecting build 17666, check out Microsoft’s official blog post.

If you encountered any bugs after installing Windows 10 Redstone 5 build 17666 on your machine, let us know in the comments below.