Trying to login with your xbox account on a mobile device shows up an error message, and cause crash. I've tried on two different mobile devices, both Android, and both of them ends up with the app crashing. I've tried even to logout and then login with the xbox app, which I succede multiples time, and then trying again directly in minecraft but it was useless
Thank you for your report!
We're actually already tracking this issue at MCPE-100100, so I will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki