The free upgrade to Windows 10 was supposed to run smoothly for everyone, but since the company started allowing users to install the operating system, we’ve come across plenty of reports pointing to various problems experienced during installation.

And the one we’ve found today is pretty much the worse you could get.

According to a number of bug reports published on Microsoft Community, a number of users who tried to install Windows 10 end up with an error reading “missing operating system,” which not only prevents them from booting back in Windows but it actually makes their computers completely unusable.

“Upgrade was going very, very well, and after the installer got to around 89%, the computer rebooted, during the reboot, the BIOS screen appears with a black screen and ‘Missing Operating System.’ This was doing an in-place upgrade...” one of the users who received the error says.

You’d better contact Microsoft

Since Windows fails to boot completely, it’s really difficult to repair the issue if you don’t have a disc or USB drive to reinstall the operating system or restart the upgrade, so a company representative says that everyone getting this error should contact Microsoft and ask for help.

“While the vast majority of our customers will be able to seamlessly upgrade, some app or device incompatibilities may exist and will decrease over time,” Microsoft explains in a statement.

Now, there seems to be some sort of pattern here, judging by user reports, but it’s hard to tell whether this is 100 percent accurate or not. Most of the users hit by the error claim they were using ASUS laptops with SSDs, so maybe Windows 10 has some sort of compatibility issue that prevents files from being correctly deployed on a computer with this configuration.

We’ve also reached out to Microsoft to ask for more information on this error and will update the article as soon as we get an answer.

I had a BSOD during my first upgrade attempt and then again after installing it. In my case windows 10 fails to boot due to my scanner being turned on which can only mean that windows 10 is having all sorts of incompatibility issues with different hardware.

too manny hit on Cortana!!and Cortana shuts you down! Stop hitiing!Is a orginal windows or it is a pirated! Some microsoft toolkit do not wok with some windows versions! tray another version! work perfect at my pc! driver usege. a driver pack solution for your new driver ! some of hardware will not work with windows 10 ! search to another forums for drivers and compability! regards ivan