Realm can't change my world

Put the summary of the bug you're having here

What I expected to happen was...: Can change my world in Minecraft PE Realm
Describe what you thought should happen here

What actually happened was...: Always tell me error
Describe what happened here

Steps to Reproduce:
1. Open your Minecraft PE and change your world
2. In the update page wait a moment
3. Always in update page, Minecraft PE well tell you "Can't find upload location" or "error".

4. I first time have this problem, it tell me "can't find update location", but my world always save in my phone not SD card. And now just tell me "error", even have not tell me why.