I have recently had some issues when the server auto saves. I am getting this for a few chunks but it started with just one a few weeks ago.
[21:36:27] [Server thread/ERROR]: Failed to save chunk -25,9
java.lang.RuntimeException: Too big to save, 1044652 > 1048576
at byi.a(SourceFile:244) ~[server.jar:?]
at byi$a.close(SourceFile:231) ~[server.jar:?]
at java.util.zip.DeflaterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at java.io.FilterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at java.io.FilterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at byj.a(SourceFile:61) ~[server.jar:?]
at byg.a(SourceFile:58) ~[server.jar:?]
at uw.a(SourceFile:699) ~[server.jar:?]
at uw.a(SourceFile:430) ~[server.jar:?]
at java.util.concurrent.CompletableFuture.uniAccept(Unknown Source) [?:1.8.0_221]
at java.util.concurrent.CompletableFuture$UniAccept.tryFire(Unknown Source) [?:1.8.0_221]
at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source) [?:1.8.0_221]
at uw.b(SourceFile:411) [server.jar:?]
at uw.a(SourceFile:388) [server.jar:?]
at vi.a(SourceFile:337) [server.jar:?]
at vk.a(SourceFile:316) [server.jar:?]
at net.minecraft.server.MinecraftServer.b(SourceFile:835) [server.jar:?]
at uk.b(SourceFile:343) [server.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:774) [server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:642) [server.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_221]
This is likely due to chunk corruption; a single chunk should never require more than ~1 MB of space (this is a limit imposed by the region file format itself, which allows up to 255 sectors of 4 KB each), which is around 20% of the typical size of an entire region file (around 5 MB for 1024 chunks, so most chunks are only 1 sector or 4 KB in size with some being larger). Either that, or somebody was playing around with commands (e.g. you can nest chests inside of chests to give a ridiculous amount of data stored in a single chest), but it should never happen in vanilla (even my "triple height terrain" world with 3 times the normal ground depth only has region files up to 10 MB in size, averaging 2.5 sectors per chunk, which is still only 1% of the maximum, while other worlds average around 5 MB for vanilla and up to 7 MB for modded worlds).
I don't know if it works for the latest version but based on a closed issue Minecraft Region Fixer appears to support at least 1.13 (which made major changes to the save format, with 1.14 making some additional changes); this might not be able to detect all issues though (MCEdit would be more useful but it unfortunately hasn't been updated past 1.12). NBTExplorer could also be used to examine and/or delete the suspect chunk (-25, 9, which would be in region file r.-1.0.mca, which may be unusually large. I suspect the issue lies in an entity / tile entity, which are listed separately from block data, which should never cause issues by itself since the maximum size is well-defined). The simplest fix would be to delete the chunk but if there is anything important in it it would be better to try to save it.
Of note, there is an open report on the bug tracker regarding this issue in 1.14 so there very well could be a bug in 1.14 itself (which also has an issue with chunks swapping, the latter reportedly being fixed in 1.15. Both have also been reported in previous versions, though I've only seen "chunk/packet too big" happen with regards to modded versions; as mentioned before, no chunk should ever get too big to be saved):
Thank you for the explanation it was very helpful. I downloaded the NBTExplorer and deleted the troublesome chunks and the messages stopped happening along with my average tick time going down from 30 to 7.
I have recently had some issues when the server auto saves. I am getting this for a few chunks but it started with just one a few weeks ago.
[21:36:27] [Server thread/ERROR]: Failed to save chunk -25,9
java.lang.RuntimeException: Too big to save, 1044652 > 1048576
at byi.a(SourceFile:244) ~[server.jar:?]
at byi$a.close(SourceFile:231) ~[server.jar:?]
at java.util.zip.DeflaterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at java.io.FilterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at java.io.FilterOutputStream.close(Unknown Source) ~[?:1.8.0_221]
at byj.a(SourceFile:61) ~[server.jar:?]
at byg.a(SourceFile:58) ~[server.jar:?]
at uw.a(SourceFile:699) ~[server.jar:?]
at uw.a(SourceFile:430) ~[server.jar:?]
at java.util.concurrent.CompletableFuture.uniAccept(Unknown Source) [?:1.8.0_221]
at java.util.concurrent.CompletableFuture$UniAccept.tryFire(Unknown Source) [?:1.8.0_221]
at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source) [?:1.8.0_221]
at uw.b(SourceFile:411) [server.jar:?]
at uw.a(SourceFile:388) [server.jar:?]
at vi.a(SourceFile:337) [server.jar:?]
at vk.a(SourceFile:316) [server.jar:?]
at net.minecraft.server.MinecraftServer.b(SourceFile:835) [server.jar:?]
at uk.b(SourceFile:343) [server.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:774) [server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:642) [server.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_221]
Any ideas?
This is likely due to chunk corruption; a single chunk should never require more than ~1 MB of space (this is a limit imposed by the region file format itself, which allows up to 255 sectors of 4 KB each), which is around 20% of the typical size of an entire region file (around 5 MB for 1024 chunks, so most chunks are only 1 sector or 4 KB in size with some being larger). Either that, or somebody was playing around with commands (e.g. you can nest chests inside of chests to give a ridiculous amount of data stored in a single chest), but it should never happen in vanilla (even my "triple height terrain" world with 3 times the normal ground depth only has region files up to 10 MB in size, averaging 2.5 sectors per chunk, which is still only 1% of the maximum, while other worlds average around 5 MB for vanilla and up to 7 MB for modded worlds).
I don't know if it works for the latest version but based on a closed issue Minecraft Region Fixer appears to support at least 1.13 (which made major changes to the save format, with 1.14 making some additional changes); this might not be able to detect all issues though (MCEdit would be more useful but it unfortunately hasn't been updated past 1.12). NBTExplorer could also be used to examine and/or delete the suspect chunk (-25, 9, which would be in region file r.-1.0.mca, which may be unusually large. I suspect the issue lies in an entity / tile entity, which are listed separately from block data, which should never cause issues by itself since the maximum size is well-defined). The simplest fix would be to delete the chunk but if there is anything important in it it would be better to try to save it.
Of note, there is an open report on the bug tracker regarding this issue in 1.14 so there very well could be a bug in 1.14 itself (which also has an issue with chunks swapping, the latter reportedly being fixed in 1.15. Both have also been reported in previous versions, though I've only seen "chunk/packet too big" happen with regards to modded versions; as mentioned before, no chunk should ever get too big to be saved):
MC-151330 Failed to save chunk: java.lang.RuntimeException
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 for the explanation it was very helpful. I downloaded the NBTExplorer and deleted the troublesome chunks and the messages stopped happening along with my average tick time going down from 30 to 7.