Not all bedrock is replaced with deepslate when updating some worlds to 1.18

Do you have a copy of the world from before you updated it? If so, could you attach it to this ticket? If it's too large to attach, you can upload it to a site like OneDrive or Dropbox and then share the link.

got this problem too, i have a world converted from java to bedrock from like 5 years ago and it only happens in java generated terrain , in bedrock generated terrain everything works as intended all after updating the world from last official 1.17 build to 1.18  onedrive link of my world

This 1.17.11 copy of world. You can go to same coordinates as on screenshot, I have hole in bedrock and big area there. Also when you update world to 1.18 you'll see what bedrock hole move down with bedrock level to -64. I hope it's not a bug, its implemented, because I don't want to lose my bedrock hole

https://www.dropbox.com/s/ypamimw8w8kuop8/FOR%20JIRA.mcworld?dl=0

I can also confirm this issue on iPadOS. My world is quite old (was started since before the nether was added, as evidenced by the nether reactor tower!) so maybe that has something to do with it? Here’s a 1.17 copy of my world:

This effect is also reproducible with a fresh 1.17 World.

My guess is that the intended way of Bedrock replacement is only between Y=1 & >=5 and only if the bedrock is solid until Y=1.
For example if there is bedrock on Y=5 but air on Y=4, the on Y=5 is not being replaced.
This has the side-effect that bedrock is not always replaced, especially on older worlds.

Steps to Reproduce:
1. Generate a new world in 1.17.41.1 with the seed "-1957154863"
2. Teleport to the coordinates +7 +2 +4
(You should be in a water pool at the bottom of the world, where some parts of the bedrock are overwritten with water)
3. Upgrade the world to 1.18.0

Observed Results:
Bedrock, that had not bedrock fully underneath all the way to Y=1 is still there.

Expected Results:
All Bedrock between Y=1 and Y=5 prior to 1.18.0 is replaced with deepslate.

Attached:

Thank you for fixing this! Developers

So right now I was wondering if I first update my worlds to, say 1.18.0 or 1.18.1, then I open the worlds with 1.18.2, will those bedrocks be replaced properly?

As of 1.18.2 on the PS4, I'm still having this issue on a realm managed by a friend of mine, where most of the bedrock around y=0 has been replaced with deepslate except for a few clusters of bedrock here and there. I really hope this can be resolved soon, seeing as how this is quite frustrating when trying to clear out an area reaching to -y levels.

It appears that a world already converted to 1.18.0 with the bedrock issue, is not updated woth 1.18.2.  You can still convert a pre 1.18 copy of the world to 1.18.2, if you saved one.  And that does fix the bedrock issue.

However I've spent many hours making updates to my world in 1.18.0 and I don't want to lose all that.  So am I just out of luck?  Or is there a way to re-convert a world already converted to 1.18?

With the 1.18.2 Hotfix this is definitely NOT still resolved. I have a world from 1.17 that I had a mine built in, dug down to try and get to the below 0 levels with new generation, and there is literally 5 blocks of bedrock in my way still. I downloaded the world from my Realm just to make sure it was actually considered updated, and still the bedrock exists. I have older downloaded versions from my realm in creative from before the update and hotfix dropped and those DID have access to the new world generation. I have no idea if this is a continued issue just with Realms worlds or not, but it is very frustrating as I just started this world to enjoy Caves and Cliffs and would rather not have to start all over AGAIN just to get to the new world gen.