Jeroen45

@ampolive I have just tested this in singleplayer, and have gotten the same errors. After this, I restarted the whole pc my server was running on, after which the error started showing up again on the server too, even though sync-chunk-writes turned to true. I have no idea what caused the errors to disappear earlier now, I'm sorry for causing any confusion. I have edited my earlier comment to reflect this new knowledge. The different error that also showed up a lot for me might still be interesting though, so I'll leave that up. Please let me know if I can still do anything else to help.

I don't know if this is related, but today I've changed sync-chunk-writes=false to sync-chunk-writes=true within my server.properties file to try and solve an unrelated issue we had (minecarts getting jammed after unloading the chunks they are in).

Surprisingly, this completely fixed the massive spam of these errors in the console. After this, I turned it back to false and loaded/walked into an area in the world that would always spam a bunch of errors. I could reliably get the errors to be spammed when sync-chunk-writes was turned to false, and then not get a single error with sync-chunk-writes turned to true. I have also ran the server with sync-chunk-writes turned to true for about a day now, and haven't gotten an error since.

It was not related, please read my later comment. The below error might still be interesting though, I can reliably reproduce that one in my world too.

Something else interesting, besides the MapLike error, we also frequently got spammed a slightly different error:

[00:53:05] [Server thread/ERROR]: Invalid bounding box data, inverted bounds for: dar{minX=2147483647, minY=2147483647, minZ=2147483647, maxX=-2147483648, maxY=-2147483648, maxZ=-2147483648}
[00:53:05] [Server thread/ERROR]: Exception loading structure piece with id minecraft:jigsaw
java.lang.IllegalStateException: Invalid call to EmtyPoolElement.getBoundingBox, filter me!
	at cxt.a(SourceFile:39) ~[server.jar:?]
	at dbg.<init>(SourceFile:57) ~[server.jar:?]
	at cud.a(SourceFile:151) ~[server.jar:?]
	at cnj.a(SourceFile:415) ~[server.jar:?]
	at cnj.a(SourceFile:175) ~[server.jar:?]
	at abe.l(SourceFile:512) ~[server.jar:?]
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(Unknown Source) ~[?:?]
	at aqv.c(SourceFile:151) ~[server.jar:?]
	at abp$a.c(SourceFile:528) ~[server.jar:?]
	at aqv.z(SourceFile:125) ~[server.jar:?]
	at abp$a.z(SourceFile:537) ~[server.jar:?]
	at abp.d(SourceFile:280) ~[server.jar:?]
	at net.minecraft.server.MinecraftServer.bf(SourceFile:776) ~[server.jar:?]
	at net.minecraft.server.MinecraftServer.z(SourceFile:764) ~[server.jar:?]
	at aqv.bp(SourceFile:110) ~[server.jar:?]
	at net.minecraft.server.MinecraftServer.y(SourceFile:748) ~[server.jar:?]
	at net.minecraft.server.MinecraftServer.x(SourceFile:701) ~[server.jar:?]
	at net.minecraft.server.MinecraftServer.a(SourceFile:270) ~[server.jar:?]
	at java.lang.Thread.run(Unknown Source) [?:?]

By the way, EmtyPoolElement is not a typo, that's actually what it says in the logs.
I hope all this information helps somehow.

Still happens in Snapshot 16w20a.
Also, for some reason I only get Villager and Sheep errors(also in 1.9 where I started getting this issue)
Even more confusing: it only happens when I enter or leave a specific region in the world, which was generated after updating my server to 1.9.