Upgraded to Windows 10 from Windows 7 and some device doesn't work? Maybe your multifunction printer work but doesn't scan? Here's a possible solution.

This seems to be a common enough occurrence, now especially with the surge of last minute updates to Windows 10. A typical scenario seems to be, for example, that a multifunction printer scanner stop being usable. Many more-than-5-years-old devices, still perfectly functional, may not be actively supported by the manufacturer, so you have to make it work with the latest available Windows 7 drivers. Searching online typically lead to a seemingly endless list of spam sites with wall of text mixing drivers, printers, scanners, and so on.

Fact is, most of the time the Windows 7 driver would be perfectly functional, and the only problem is that it's not signed! So it's just a matter of temporarily disable the driver signature verification. Here's what you can try:

• be sure to have the Windows 7 drivers at hand: either download it from the manufacturer website and unzip it in a folder, or verify that you have a folder named "Windows.old" in you root directory (that would contain all the interesting bits and pieces of your previous installation; if you just upgraded, it's certainly there)
• From the Start menu go into Settings
• Click to Updated & Security, and then on Recovery
• Then click on Restart Now, under Advanced Setup

The system will present a new menu:

• Click Troubleshoot
• Click Advanced Options
• Click Startup Settings
• Click Restart

The system will reboot, and present a list of available options \ tweaks.
Just hit 7 to temporarily disable drivers signatures verification!
N.B. This exclusion will be active only for this session. At the next reboot, all will be business as usual.

As soon as the system restart, go to start, search for "devices manager".
You should see the problematic device with a yellow alert sign. Right click on that devices to access his properties, and select Update driver. Choose to manually specify the driver location, and point the system to either the folder where you prepared the drivers files, or to the Windows.old folder mentioned above.

With a bit of luck, Windows 10 will say that it has found the driver, and ask for a confirmation to install the unsigned driver! Confirm, and verify if you solved your issue.
Reboot as soon as possible to restore the normal driver verification process.

Hope this helps!