(This happens for me in Singleplayer; I add this note as it seems that Searge specifically needs it happening not on SMP but Singleplayer)
I started up my Bug Testworld in 1.10.1 and crashed.
This happens each time I open up the world in 1.10.1.
It does NOT crash if I open the world in 1.10.
"Description: Server forgot to send required information to construct BlockEntity"
"BlockEntity missing instance data"
BlockState: minecraft:command_block[conditional=false,facing=north]
Block coordinates: World: (18,65,32), Chunk: (at 2,4,0 in 1,2; contains blocks 16,0,32 to 31,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
To verify that the CB it points at is NOT (or not solely?) the reason for it, I deleted the CB in 1.10, reopened the worldsave again in 1.10.1 and got a crash again, this time:
BlockState: minecraft:command_block[conditional=false,facing=east]
Block coordinates: World: (39,65,53), Chunk: (at 7,4,5 in 2,3; contains blocks 32,0,48 to 47,255,63), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
—
Edit 1: Just saw that Searge requested for it: https://twitter.com/SeargeDP/status/745602435612282880
Edit 2: Provided a world download for him/link is sent.
Linked issues
Attachments
Comments


Can you also link the world download on here please?
A good way to reproduce this is to reload the world while a piston is triggered.
I attached a world in which each tick one piston fires, which probably guarantees the crash.
In the linked crash reports it's a command block, but it likely has the same cause.

We have enough data from the pistons, this is somehow caused by a commandblock.
I didn't see any info about pistons here. I assume there is another report?
It might be worth linking the reports together then, as it clearly is the same crash message and both cases were added in 1.10.1, so it's not far off to assume that this has the same cause.


Resolving to MC-103981, please provide any new information there.

@Meri - able to get me a copy of that world?
Thanks
That's a new one, please do provide that world download.