Pre-existing Flat worlds are broken In the new update (1.17.30) for bedrock. Atleast for me anyway. So i open Minecraft, see a new experimental feature called "Experimental Molang features" (and yes, that is with an L) and i turn it on and open the flat world i was working on. Then i see that theres a big hole of missing chunks that my builds were on. So i started testing on different worlds. Tested it on a normal world, didn't break. So it was just on flat worlds. At first i thought it was because of the new experimental feature but i got onto a different pre-existing flat world without turning on the new experimental feature and it was broken. So that means its just the update that breaks the flat worlds, not the experimental feature. I did try making a new flat world on this version and it was fine. So old flat worlds are the only ones broken. And this happened. I put my backup world on MC and opened it. It was broken too. So even my backup worlds were broken even tho I didn't make those backup worlds on this new version. So will this be fixed or my flat worlds are corrupted forever?
MCPE-142219
Pre-existing Flat worlds are broken
Resolved
Incomplete
2
As part of my work here on the bug tracker, I use flat worlds for testing bugs every day, and I usually don't create a new one for new releases. I've opened a couple that I've had around for a while under 1.17.30 and they're fine. So in general, pre-existing flat worlds are not broken.
Since you haven't provided enough information for me to reproduce this issue, I am closing this report as Incomplete. If your intention was to report an actual bug (as opposed to asking for community support, which is not something we provide), you are welcome to do so following our guidelines. Please be sure to avoid duplicating an existing report of the same bug by using the search function.
However, I have a hunch that I know what happened in your case, and if I'm right there is no bug. I think the worlds that get ruined in 1.17.30 were already experimental in 1.17.11, probably because you had already turned on Caves and Cliffs experiments by then. And like a lot of people, you let yourself build with the new features despite being shown the following warning:
[media]Notice that last sentence: "The new world might crash, break, or not work with later updates." Mojang tries very hard to maintain a world's ability to upgrade to a later release, but it isn't always practical, so they warn you that it might not work.
Unfortunately, the fact that it usually does work has trained people to disregard the warning: They build with beta/experimental features as if they were complete and finished, and before long going back to the safe backup would cancel too much progress so they delete the backup and make the experimental world their only copy. And I expect that's what you've done.
When you updated to 1.17.30 and turned on the Molang experimental toggle, you didn't get warned again because it was already an Experimental world. So maybe you didn't remember the warning you got when you turned on Caves and Cliffs in 1.17.11. But with respect to then, the new release is a "future update" and there was no guarantee that you'd be able to upgrade it. In fact, I suspect that it's especially unlikely to succeed because of how substantially world structure is changing from 1.17 to 1.18 and how much the scheme for upgrading it has changed as we've progressed through Beta releases.