Hendrik van Dijk

I haven't been able to replicate it anymore. I started a new world (I died in the previous hardcore) and I haven't had the problem anymore. But you might want to keep this open for people to link it if they have any problems.

Thank you for your help, Violine1101! You and the others are a huge help in making this game even better. After playing it since September 2010 I still love it and the direction it is going!

I am uploading the World File now.

I have replaced some Barrels but in the tower up on the hill, there is still one that produces it.

I started this world in one of the snapshots of the 1.14 update a few months ago. Might that be the cause? The updating of the world with different snapshots?

https://1drv.ms/u/s!Ag_zvQnoI6vBkZ9vpCMdE8Ox0erQfA

I found a barrel that was placed since one of the previous versions and when I opened it I got this message:

The game crashed whilst ticking block entity
Error: java.lang.IllegalStateException: POI never registered at eu{x=-142, y=97, z=181}

Then there was also a new error log. I hope this helps.

Hey Violine1101. Okay, so here is the thing I found out. 
The first time when it crashes I get the error that you described.

Then, when I reopen the world it crashes 1-2 times as soon as I see "joining world".

That is when the crash report comes in.

I guess the save is still going through the process that caused the ticking error? (if you can confirm)

But puting Smooth lighting on maximum reduces the blackness of the 'shadow'

It also happens when stairs are placed upside down and a slab in the middle.
This is a sewer that I made and it depends on what is placed above ground what the lighting will be like in the sewer. I tried different things but nothing solves it.