Honestly, I don't even know where to start. I got a hold of many copies of my old worlds, about 6 years old. Maybe minecraft version 1.8.6.
The problem is... Once I enter the world, there are random chunks all over the map that get generated. There doesn't seem to be any rhyme or reason why they get generated. And it basically generates right over my old creations. The old chunk (Z axis, going upwards) are still there. So it doesn't seem like the old chunks were corrupted. It's just that the game decides to randomly generate chunks.
Maybe there is an option to turn off chunk generation once I enter a map?
Did you just open the old map in new version skipping the versions inbetween, or did you open it in all previous versions until you got to the current version?
This shouldn't be an issue - unless you fly around to load every chunk or use the "optimize world" feature (only since 1.13) only chunks around spawn and the player (within render distance) will be loaded so the game has to be able to handle chunks from every version back to 1.2 (older worlds had to be converted, which was done all at once), and even then it can still convert even older worlds.
If anything, it should be safer to load worlds in newer versions, for example, the following bug report is about an issue that happened when upgrading worlds created in Beta to 1.8, even if you had opened in in versions in between (mind also what I said about only loaded chunks being updated); the last comment says that upgrading straight to 1.15.2 caused no issues:
There is also a chunk corruption bug in newer versions, which can happen to any world but may be more likely when upgrading (it seems to be an issue with the chunk saving system and upgrading a world causes a lot of chunks to be modified and saved at once; using the "optimize world" option may reduce the chance of issues since the game isn't attempting to run the world at the same time):
Otherwise, you should submit a bug report, including a download of the world itself (you only need to include at least one region file that replicates the issue as worlds can be quite large) so Mojang can fix it. It is important to note though that if you ever used any mods or world editing software the issue will likely be closed as invalid as these have been linked to chunk corruption (see the issue regarding chests, which was due to older versions using different data values which newer versions can't handle, even if they behaved properly in older versions; mods can likewise leave behind data that isn't removed by the game).
webrosc: I just opened the map directly through the game, was I supposed to do it some other way? So in other words, yes, I "skipped" over all previous versions.
TheMasterCaver: I did fly around, I don't understand what the problem is or what you mean by "load every chunk".... I don't understand what the optimize world problem is either, sorry.
For now I'll see if I can submit a bug report... and I don't see how it could be misplaced chunks since I didn't saw any of them being in the wrong place. Just random nature chunks being generated on top of my old stuff.
edit: okay so I found out that I can actually pick to play one of the old versions of minecraft, so I'm gonna test and see... thanks for the tips so far.
edit2: any idea why my map is 100% empty when I load it? version up to 1.12.2 is empty, then 1.13 upwards can load the map BUT 20% of chunks get generated.
edit2: any idea why my map is 100% empty when I load it? version up to 1.12.2 is empty, then 1.13 upwards can load the map BUT 20% of chunks get generated.
Are you absolutely sure that the world was last loaded in 1.8.6? This is an odd version as it was only out for about a week before 1.8.7 came out (May 25-June 5, 2015). The behavior that you describe, if "empty" means that all chunks were regenerated (not missing/only air), is what happens when you load a world from 1.13 or later in an older version since 1.13 completely changed the save format so older versions don't recognize any valid chunks and just recreate them from scratch. Downgrading older versions, e.g. 1.12 to 1.8, may also cause chunks to reset but it will be random since this is mostly due to invalid entities and other non-block data and not every chunk has entities (invalid blocks themselves will be removed). The modification dates of the files can give a clue as to what the latest version was, assuming you regularly updated to newer versions.
You can also try opening the world with MCEdit, which will only work if it is from 1.12.2 or earlier (it can't read the newer save format), and see if the chunk corruption isn't pre-existing (corrupt chunks will not load and/or give an error), as well as analyze the world (or at least the area around your builds) and examine chest contents to see if there are blocks and items from newer versions (e.g. a list of blocks and items added in 1.9, with other versions accessible from the box on the top-right; only major versions, e.g. 1.8, 1.9, 1.10 generally add new features).
Otherwise, there is a thread for fixing corrupted saves, although the people fixing them haven't been that active lately so it may take a while to get a response; be sure to leave a description of the issue and a link to a download of the world:
No, I'm not sure at all about the version, is there any way for me to find out? I got several versions of several save files. I can see folders .minecraft/versions/1.8.6 and 1.8.7 and also 1.6.2 1.7.2 1.7.10 ... I'll test more and see, thanks a lot for all the info, just wanted to reply to acknowledge your help. And yes MCEdit was exactly what I used, I will try it out.
Honestly, I don't even know where to start. I got a hold of many copies of my old worlds, about 6 years old. Maybe minecraft version 1.8.6.
The problem is... Once I enter the world, there are random chunks all over the map that get generated. There doesn't seem to be any rhyme or reason why they get generated. And it basically generates right over my old creations. The old chunk (Z axis, going upwards) are still there. So it doesn't seem like the old chunks were corrupted. It's just that the game decides to randomly generate chunks.
Maybe there is an option to turn off chunk generation once I enter a map?
Bump
This shouldn't be an issue - unless you fly around to load every chunk or use the "optimize world" feature (only since 1.13) only chunks around spawn and the player (within render distance) will be loaded so the game has to be able to handle chunks from every version back to 1.2 (older worlds had to be converted, which was done all at once), and even then it can still convert even older worlds.
If anything, it should be safer to load worlds in newer versions, for example, the following bug report is about an issue that happened when upgrading worlds created in Beta to 1.8, even if you had opened in in versions in between (mind also what I said about only loaded chunks being updated); the last comment says that upgrading straight to 1.15.2 caused no issues:
MC-70813 Chests missing when upgrading world from 1.7.x to 1.8
There is also a chunk corruption bug in newer versions, which can happen to any world but may be more likely when upgrading (it seems to be an issue with the chunk saving system and upgrading a world causes a lot of chunks to be modified and saved at once; using the "optimize world" option may reduce the chance of issues since the game isn't attempting to run the world at the same time):
MC-161823 Chunks can occasionally be misplaced upon loading a world
Otherwise, you should submit a bug report, including a download of the world itself (you only need to include at least one region file that replicates the issue as worlds can be quite large) so Mojang can fix it. It is important to note though that if you ever used any mods or world editing software the issue will likely be closed as invalid as these have been linked to chunk corruption (see the issue regarding chests, which was due to older versions using different data values which newer versions can't handle, even if they behaved properly in older versions; mods can likewise leave behind data that isn't removed by the game).
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
webrosc: I just opened the map directly through the game, was I supposed to do it some other way? So in other words, yes, I "skipped" over all previous versions.
TheMasterCaver: I did fly around, I don't understand what the problem is or what you mean by "load every chunk".... I don't understand what the optimize world problem is either, sorry.
For now I'll see if I can submit a bug report... and I don't see how it could be misplaced chunks since I didn't saw any of them being in the wrong place. Just random nature chunks being generated on top of my old stuff.
edit: okay so I found out that I can actually pick to play one of the old versions of minecraft, so I'm gonna test and see... thanks for the tips so far.
edit2: any idea why my map is 100% empty when I load it? version up to 1.12.2 is empty, then 1.13 upwards can load the map BUT 20% of chunks get generated.
Are you absolutely sure that the world was last loaded in 1.8.6? This is an odd version as it was only out for about a week before 1.8.7 came out (May 25-June 5, 2015). The behavior that you describe, if "empty" means that all chunks were regenerated (not missing/only air), is what happens when you load a world from 1.13 or later in an older version since 1.13 completely changed the save format so older versions don't recognize any valid chunks and just recreate them from scratch. Downgrading older versions, e.g. 1.12 to 1.8, may also cause chunks to reset but it will be random since this is mostly due to invalid entities and other non-block data and not every chunk has entities (invalid blocks themselves will be removed). The modification dates of the files can give a clue as to what the latest version was, assuming you regularly updated to newer versions.
You can also try opening the world with MCEdit, which will only work if it is from 1.12.2 or earlier (it can't read the newer save format), and see if the chunk corruption isn't pre-existing (corrupt chunks will not load and/or give an error), as well as analyze the world (or at least the area around your builds) and examine chest contents to see if there are blocks and items from newer versions (e.g. a list of blocks and items added in 1.9, with other versions accessible from the box on the top-right; only major versions, e.g. 1.8, 1.9, 1.10 generally add new features).
Otherwise, there is a thread for fixing corrupted saves, although the people fixing them haven't been that active lately so it may take a while to get a response; be sure to leave a description of the issue and a link to a download of the world:
https://www.minecraftforum.net/forums/minecraft-java-edition/discussion/297844-official-corrupted-save-recovery-thread
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
Thank you very much for the reply.
No, I'm not sure at all about the version, is there any way for me to find out? I got several versions of several save files. I can see folders .minecraft/versions/1.8.6 and 1.8.7 and also 1.6.2 1.7.2 1.7.10 ... I'll test more and see, thanks a lot for all the info, just wanted to reply to acknowledge your help. And yes MCEdit was exactly what I used, I will try it out.