Q) I can start the Windows 10 upgrade process but it won’t complete – is there a fix?
You may have found the Windows 10 upgrade starts but then hangs, often with a somewhat unhelpful message saying Something happened. You may see an error code, too.
Log in as administrator
One thing to check is whether you’re logged in as an administrator; the upgrade may not complete if you’re logged in with a Standard user account.
Free hard drive space
Double-check that you’ve got enough free hard drive space for the upgrade file – at least 20GB is needed.
Fix corrupt Windows 10 installation files
These types of error can also be caused by a problem with corrupted installation files downloaded by Windows Update, so one solution is to delete all of these and download a fresh batch.
To do so, navigate to the C:\Windows\SoftwareDistribution\Download folder – delete everything inside (but don't delete the Download folder itself).
Then, click Start, type cmd, right-click the Command Prompt listing and select
Run as administrator.
Type wuauclt.exe /updatenow (be sure to type in a space before the forward-slash). Press Enter on your keyboard, then close the Command Prompt window and launch Windows Update (search for update to find it).
Click Check for updates. Windows Update will download the Windows 10 installation files again.