For the longest time I've had an issue where whenever I launched Minecraft Bedrock on my PC it wouldn't keep me signed in (even though I had tried launching it through the new Minecraft launcher as well as the Xbox companion app). I'd click on sign in and then I'd click on "save to Microsoft account." The Xbox thing would pop up with my Microsoft account on there, but when I'd click "Let's play" it would always immediately show the failed to login code: glowstone error.

I joined the official Minecraft discord in hopes of finding a fix and I eventually did! Someone suggested to download the Xbox app on Windows 10, sign in, and launch it through there. I did that, and when I launched Minecraft Bedrock and attempted to sign in it actually worked this time! It seems like as long as you do this once you are good from then on out, as if I simply launch Minecraft Bedrock on its own (without Xbox app) it still keeps me signed in by default.

Basically, the whole reason I post this is that I think it'd be helpful to add this solution to the "Error Code Troubleshooting" page on the Minecraft Help Center page, as it currently only suggest to keep restarting the game or just waiting for it to be fixed. I've had this issue for a couple years now, so I think if other people have this issue, this solution would be very helpful!