Nether Fortresses Not Loading Properly in 1.16

Could you provide an example seed and coordinates please?

Could you provide an example seed and coordinates please?

181, 71, 327
-1389161317

181, 71, 327
-1389161317

I saw this in my kids' worlds yesterday too. Based on testing I did for MCPE-23416, I believe what is happening is that chunks outside of the player's simulation distance but within render distance (actually render + 2) only generate if they contain a tile entity. So the fortress chunks with spawners and chests may have generated and been included in the world save in 1.14.60, but the rest of the fortress was not generated until you traveled closer to the area in 1.16. But due to the generation algorithm changing to accomodate new biomes and block types, the intervening chunks that would have contained a fortress in 1.14.60 are no longer fortress chunks in 1.16.

I saw this in my kids' worlds yesterday too. Based on testing I did for MCPE-23416, I believe what is happening is that chunks outside of the player's simulation distance but within render distance (actually render + 2) only generate if they contain a tile entity. So the fortress chunks with spawners and chests may have generated and been included in the world save in 1.14.60, but the rest of the fortress was not generated until you traveled closer to the area in 1.16. But due to the generation algorithm changing to accomodate new biomes and block types, the intervening chunks that would have contained a fortress in 1.14.60 are no longer fortress chunks in 1.16.

I concur with GoldenHelmet's analysis.

A tile entity is what the game uses to give nontrivial behavior to something that can be placed like a block. In cases like this, the tile entity is usually a monster spawner.

What happened is that the spawner caused the chunk it was in to be generated earlier than normal, because that's just something the game does for some reason (no doubt it's a good one, I just don't know the reason). Unless you explore closer to that area, the chunks next to the spawner aren't generated, so you have the unusual situation of generated chunks surrounded by void. You usually don't get to see it that way though, because as soon as you get close enough the missing chunks get filled in.

But if you update to a new release before filling in the missing chunks, and the new release changes the rules of world generation (changes to biomes, terrain, and/or structures), the structure containing the spawner may no longer be generated in that location. In that case the void chunks will be generated according to the new rules and won't meld with the chunk containing the spawner. (The game doesn't regenerate the spawner chunk. It doesn't ever regenerate any chunk because doing so would destroy whatever you might have built there.)

The only way to prevent this from happening would be to outlaw changes to world generation, but that would mean no new biomes or structures could be introduced any more, and nobody wants that. So this quirk can't be eliminated, but that's ok because it doesn't cause any serious problem. It only happens when you update a world to a new major release, and it only affects structures near monster spawners at locations you came close to but not too close. It doesn't continue happening as you explore fresh parts of the world. It's not exactly intended behavior because Mojang would rather it didn't happen, but it's a forced consequence of being able to make improvements to the game, so Mojang will probably say they "Won't Fix" it.

I created a new world under 1.16.0 using the seed you provided, then traveled to the coordinates you gave and took the following screenshots. The diamond block is at those exact coordinates; it is floating one block above the ledge.

As you can see, 1.16 doesn't generate a nether fortress in this area, probably because part of it would be within the new Basalt Deltas biome. Except for the presence of the spawner, your world should look identical, and if it does it confirms the above analysis.

I concur with GoldenHelmet's analysis.

A tile entity is what the game uses to give nontrivial behavior to something that can be placed like a block. In cases like this, the tile entity is usually a monster spawner.

What happened is that the spawner caused the chunk it was in to be generated earlier than normal, because that's just something the game does for some reason (no doubt it's a good one, I just don't know the reason). Unless you explore closer to that area, the chunks next to the spawner aren't generated, so you have the unusual situation of generated chunks surrounded by void. You usually don't get to see it that way though, because as soon as you get close enough the missing chunks get filled in.

But if you update to a new release before filling in the missing chunks, and the new release changes the rules of world generation (changes to biomes, terrain, and/or structures), the structure containing the spawner may no longer be generated in that location. In that case the void chunks will be generated according to the new rules and won't meld with the chunk containing the spawner. (The game doesn't regenerate the spawner chunk. It doesn't ever regenerate any chunk because doing so would destroy whatever you might have built there.)

The only way to prevent this from happening would be to outlaw changes to world generation, but that would mean no new biomes or structures could be introduced any more, and nobody wants that. So this quirk can't be eliminated, but that's ok because it doesn't cause any serious problem. It only happens when you update a world to a new major release, and it only affects structures near monster spawners at locations you came close to but not too close. It doesn't continue happening as you explore fresh parts of the world. It's not exactly intended behavior because Mojang would rather it didn't happen, but it's a forced consequence of being able to make improvements to the game, so Mojang will probably say they "Won't Fix" it.

I created a new world under 1.16.0 using the seed you provided, then traveled to the coordinates you gave and took the following screenshots. The diamond block is at those exact coordinates; it is floating one block above the ledge.

As you can see, 1.16 doesn't generate a nether fortress in this area, probably because part of it would be within the new Basalt Deltas biome. Except for the presence of the spawner, your world should look identical, and if it does it confirms the above analysis.

Confirming ticket based on the analysis given by myself and confirmed by Auldrick’s test of the seed and coordinates provided. I agree this is likely a “won’t fix” issue.

Confirming ticket based on the analysis given by myself and confirmed by Auldrick’s test of the seed and coordinates provided. I agree this is likely a “won’t fix” issue.

If you have a copy of the world available, you might like to upload a copy of it for investigation.

• On Windows 10 you can use the Export world feature.

• On Android or iOS you need to use a file explorer to navigate to Device storage > games > com.mojang > minecraftWorlds

• On Xbox or Switch the only way is to upload it to a Realm, and then download the world on Windows 10 or Android/iOS. (Please do not purchase a Realms subscription just to provide a world to us - but if you have a Realm already this may be a viable option if you wish to do so.)

If the world is larger than 10MB you can upload the world to OneDrive or a similar file sharing site, and then share the link.

If you have a copy of the world available, you might like to upload a copy of it for investigation.

• On Windows 10 you can use the Export world feature.

• On Android or iOS you need to use a file explorer to navigate to Device storage > games > com.mojang > minecraftWorlds

• On Xbox or Switch the only way is to upload it to a Realm, and then download the world on Windows 10 or Android/iOS. (Please do not purchase a Realms subscription just to provide a world to us - but if you have a Realm already this may be a viable option if you wish to do so.)

If the world is larger than 10MB you can upload the world to OneDrive or a similar file sharing site, and then share the link.

Thank you for your report!
However, this issue has been closed as Won't Fix.

This is likely to be the result of existing world generation not exactly matching the newly generated chunks. New chunks and world generation should be working though, and if you have any examples of newly generated worlds that are broken, please file a new report with seed and screenshots.

If you'd like to post a suggestion or give further feedback, please visit the Minecraft Feedback Site or choose a link below.

Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki

Thank you for your report!
However, this issue has been closed as Won't Fix.

This is likely to be the result of existing world generation not exactly matching the newly generated chunks. New chunks and world generation should be working though, and if you have any examples of newly generated worlds that are broken, please file a new report with seed and screenshots.

If you'd like to post a suggestion or give further feedback, please visit the Minecraft Feedback Site or choose a link below.

Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki