the serial port does not exist or your board is not connected

I’m suspecting the bootloader might be broken on my Gemma… When i try to upload a sketch, it fails with the error message “the selected serial port does not exist or your board is not connected”… I am using Windows 10 and this additional dialog pops up when i connect the Gemma with a USB-cord:

I’ve tried searching for various soultions, e.g reinstalling the drivers, changing the port etc. but nothing has worked so far.
Any help or suggestions on what else to try is greatly appreciated!

Are you pressing the reset button immediately before attempting to upload?

Are you trying to use it in a USB 3.0 port? The Gemma is a VUSB device (ie, doesn't actually comply with USB standard, but is "pretty close") and as a result, it is particularly prone to compatibility issues. Try connecting it through a hub.

Yes, and it's blinking red right after i press it (as it should when listening for instructions iirc).

I haven't tried using a hub, but several different cords, and the one i'm using now is USB-2.0...