Falcon Hellstrom

Glad to be of help Hunter Jones and A D C 🙂

As far as I understand every other time Minecraft changes its major version the generator changes so, if you want to try to recover it, you will have to get the minecraft version you originally had. I believe the editor shows you what version of minecraft it was created with. 

Ok, so I found how to replicate this issue.

tl;dr: this bug happens when you use /setworldspawn in an old world.

steps to replicate:

1) create old world

2) move several blocks away from the spawn point

3) /setworldspawn

4) save & quit 

5) enter again, and voila. if you go to any of the edges 2 will behave like normal old edges and the other 2 edges will let you go one chunk into the limbo.

confirmed in both Android and Win10 V1.14.60

long story: this week I found how to convert infinite worlds into old worlds, and I understood the concept that there were some coordinates I had to manipulate in order to move the old world to center it around what I wanted, and since I use old worlds to create custom maps (far easier to limit players and to avoid loading issues) I used to thought I had a very fragile world that would break almost every time I tried to modify something in it (you can see my comment from sept 7 2019). So I noticed that after several hours/days and some heavy modifications to the map, the world was still working fine. So before finishing I set the new worldspawn... and then it happened... I knew I had a backup of the dat file so I was relaxed, but then it hit me. I recalled how the concept of moving the spawn coordinates in old worlds meant where I wanted the world to center. so I decided to test it, and replicate it in a new empty old world...

so here is my test:

overall it bites 1 chunk from 2 sides where it allows you to go or see entities, and 8 chunks from another side and 6 from another side where you cant go into or see.

the only way I had found to repair this is by having a copy of your level.dat before using the setworldspawn command, but now that I understand the concept of old world coordinates manipulation, I now know you can fix it by editing the level.dat and replicate the SpawnX, SpawnZ, and SpawnY to the LimitedWorldOriginX, LimitedWorldOriginZ, and LimitedWorldOriginY like this:

[offsetting] is the original world before using the /setworldspawn and [copy of offsetting] is the world after using the command on coordinate 100, 104, -121

here are some screenshots of the bug in action!

after the bug:

and how it originally looked:

Below you can see the world size difference after the bug (left) and before the bug (right)

Update: Ok I have been having these issues more often lately, I'm not sure if it has something to do when Minecraft fails to load (I open Minecraft, starts loading then it crashes and sends me to my android screen), after several retries I get a message saying that global resources failed to load.

anyway, I noticed that the only correct way to restore these worlds is copying the .dat I explained before, but the only way I have found to fully restore it once it gets corrupted is from the same world, a previous copy. (Haven't tried with old -> infinite conversion .dat files)

So once this happens I copy the .dat from a previous copy and, voila... at least I have a way to fix this...

Can Confirm this still happens as of 1.12.0 (Android)

Please Mojang, fix this, since I mostly use old worlds since its easier to make delimited custom maps.

A tool from infinite to old would be also awesome.

What I noticed is that the world SHIFTS its boundaries by some blocks. so for example it "eats" 20 blocks, and adds 20 blocks on the other side of the map. I remember having this issue back in 2014 with mods and noticing it shifted the map.

the easy way to fix this is and see what has happened in your world is replace the .dat files from the corrupted world root folder from a fresh world. (level.dat and level.dat_old)

if you play around with these files and the files in the db folder you can make it work again. (I got mine working today, I cant recall how I did it exactly thou, I also had a copy of my world from 3 days ago) (as always make a backup)

And after this last incident I installed an autobackup app of my worlds to GDrive. I dont want to lose the days i spend making in these worlds...

with the last update, this is fixed.

works as intended, merge it with a compass in an anvil.

works as intended. when placed on an item frame, it shows current location in the map.
if you want to be marked in the map, merge it with a compass on an anvil.