You need two players in the world
player one stands on the shulker box that is facing up
Player one opens the shulker box causing him to fall into the shulker box
This action will cause player two’s game to crash but not player ones
This was repeated multiple times on a private multiplayer world with the same result each time. If player two is the host of the game player one will also undoubtedly crash aswell.
Related issues
duplicates
Comments

Thank you for your report!
We're actually already tracking this issue at MCPE-51711, so we will resolve and link this ticket as a duplicate.
If you are able to provide a copy of the world where this is happening, and attach it to MCPE-51711, that would be most helpful.
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I was playing on a realm, and most people had shulker boxes, so everyone went to one area, and someone placed, and opened the shulker box. Everyone crashed, and it kept happening. BUT no one crashed until the box opened.