According to reports and users complaints, the first Windows 10 cumulative update makes some computers to go in a 'reboot loop'. Microsoft's cumulative update for Windows 10 called KB3081424 is causing issues on the machines of some users, by sending the affected systems into an endless crash loop.

When trying to install, the update fails once it gets to a certain point. Then it displays the error message "We couldn't complete the updates, undoing the changes." Things wouldn't be so bad if stopping at this point. However, since now Microsoft is forcing its mandatory updates onto computers running Windows 10, the operating system keeps trying and failing to install the update. This causes a periodic crash/reboot loop of the system.

What makes matters even worse is the fact that most users wouldn't have the level of technical knowledge to block toxic Windows 10 updates. Since unable to prevent this update from attempting to install, users are forced to abandon their machine until a fix will be made available by Microsoft.

Attempting a fix on your own would involve some advanced registry editing in order to remove legacy junk related to old drivers installed on the machine prior to the Windows 10 upgrade. This kind of task is not something that most of the users would be comfortable with. It would also require to have a known good backup, since by deleting the wrong registry entry you can easily end up in a situation even worse.

A number of tech websites provide some instructions on how to fix the situation, but an officially sanctioned fix provided by Microsoft wasn't released yet. The instructions are just third-party interpretations of the fix and sometimes they might be written by individuals who hadn't even encountered the issue for themselves. Users can easily damage their system by following these "fixes", so it's advisable to better wait for an official fix rather than editing your registry.

It is not clear yet how widespread this issue is, but on a search on Google you will find many reports from users experiencing this problem. From reports, it is safe to say that the "reboot loop" affects only a part of the systems, especially those that keep a fair bit of legacy drivers.