I can confirm this is also an issue on an iPad Air 2, the game crashes shortly after launching whilst it is automatically signing into a child's xbox live account.
I suspect many people encounter this issue by 1) setting up an xbox account for their child with the default restrictions of the child account 2) Attempting to add a "friend" and getting a permissions error 3) Proceeding to change the child's account settings on xbox live to make it less restrictive.
Now every time Minecraft is launched it will try to automatically login to the child's xbox live profile and immediately crash.
Please get it assigned and fixed!
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The following settings appear to work at making online multiplayer possible on a child's account
Login to xbox live (account.xbox.com)
Click your user profile in top right and select [Xbox settings]
Select Privacy & online Safety
Select your child's profile
Select Xbox One/Windows 10 Online Safety
Ensure the following settings are enabled
Select Xbox 360 Online Safety
Enable Online Gameplay
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Here is a workaround for an iPad Air 2 4G if Minecraft is crashing after the above steps:
Disable WiFi only (not airplane mode, no SIM inserted)
Settings -> Profile -> Sign Out for Xbox Live -> Sign Out
Enable WiFi
Sign back in with the child's account
I'm having the same issue, any update?