Fix Windows 10 Build 16226 Install Fails Due to .NET 3.5 Migration

Today Windows Insider team released Windows 10 build 16226 for PC to Fast Ring Insiders members. The new build comes with new features, bug fixes, and other improvements. However, for some users PC may fail the install during the SafeOS phase of the install (“Working on Updates” between 0% and 30%) and roll back to your currently installed build. There is a known issue with the .NET 3.5 migration that causes the new OS installation to fail. Check out the workaround below.

Here are official Workaround Steps:

Before attempting to install build 16226, or if you have .NET 3.5 installed and OS build 16226 install fails, complete the following steps:

(If you have not yet attempted to install 16226, skip to step 3)

  1. Wait for your PC to successfully roll back to your current build
  2. Log into your machine
  3. Open Control Panel
  4. Select Programs
  5. Under “Programs and Features” select Turn Windows features on or off
  6. Un-select the box next to .NET Framework 3.5 (includes .NET 2.0 and 3.0)


  7. Click OK
  8. Allow Windows to complete the necessary removal operations
  9. Reboot your PC
  10. Navigate to Settings > Update & Security > Windows Update and attempt to install 16226.

Once the install is completed, return to step 3 and re-install the .NET 3.5 feature. Reboot your PC one final time and you should now be updated and ready to go.