One of my bugs is that fences or redstone dust aren't connected, when i load my world in the new shapshots. When I load it in 1.12.2 it works all as intended. Pictures with coordinates(picture 2,3,4,5): https://imgur.com/a/mCKiv
My world (1.12.2):http://www.mediafire.com/file/mugx846yni1bvy8/New_World_snapshot_3_1_in1_12_2.zip
My world(18w10d): http://www.mediafire.com/file/b2338fw66pn4jc3/New_World_snapshot_3_1_in_10w18d.zip
Linked issues
duplicates 1
Comments 6
I opened my world in 1.12.2 and went to the areas. I exit the game and load the world up in 18w10d and it indeed spawned correctly, maybe it is fixed, or maybe it just randomly spawns abnormal? Or maybe it had something to do with the amount of entities i first had (had around 650).
But when I do load it in 1.12.2 and go to the spawn chunks, exit the game and load it up in 18w10d it still crashes. (but this is another thread)
Tried to reproduce by loading the world while I was neither at spawn nor at the affected area. Didn't work. Weird.

I think this is a duplicate of the "relates to" link, but with more information.
I noticed the same behavior for redstone dust found in some jungle temples in a newly generated world, but I couldn't determine the criteria for reproducibility.
Resolving to MC-125625. If you are able to reproduce redstone not upgrading correctly, please create a separate ticket.
I loaded your 1.12.2 world in 1.12.2, went to the affected area, and then opened it in 18w10d. Everything looked normal. What area were you in when you first loaded the world in 18w10d?