Similar to windows 8.1 update issues, it appears the new Windows 10 does occasionally have the same problem. With such problems, your PC may restart repeatedly showing the message below.
We couldn’t complete the updates, undoing changes.
Here are some steps to fix this.
Boot Into Safe Mode
Basically, you have to Restart > Advanced Options > Safe Mode > Boot into safe mode … and uninstall the most recently downloaded updates. More information on how to do this can be found from my previous post on windows 8.1 update issues here .
Remove non-existent users from Registry
This issue is known to be related to the particular error code 0x80070003 .
Installation Failure: Windows failed to install the following update with error 0x80070003: Security Update for Windows 10 for x64-based Systems (KB3074683).
You can find out which exact error code you are experiencing using the event viewer.
To view error event logs for applications
You must be logged on as an administrator to perform these steps.
Open Event Viewer by clicking the Start button , clicking Control Panel, clicking System and Security, clicking Administrative Tools, and then double-clicking Event Viewer. If you’re prompted for an administrator password or confirmation, type the password or provide confirmation.
In the left pane, double-click Applications and Services Logs, browse to the specific program that had an error, and then review any error events for that program.
Double-click an event to view a description and to find links to more information.
In this case, a solution is to look through the user profiles in your Registry
A guide on how to modify Registry Keys can be found here.
Remove any users that do not exist. Sometimes, some windows services may create user profiles (e.g IIS web service or other services) which may be deleted after uninstalling the service but the user profiles remain in registry.
Note : Before modifying your registry, remember to back it up first.
Other Windows 10 Installation Errors
Microsoft has put together a list of some possible errors and their fixes here.
If All Else Fails – Uninstall Most Recent Updates
While still in Safe Mode, try to uninstall the most recent updates … keep uninstalling until you are able to boot into your desktop normally.