My Minecraft server crashes very often. Why?

My CityBuild Server crashes very regularly with the following error. Can someone tell me something about it? Is there not enough RAM on the server?

java.util.concurrent.CompletionException: net.minecraft.server.v1_16_R3.ReportedException: Exception generating new chunk

at java.base / java.util.concurrent.CompletableFuture.encodeThrowable (CompletableFuture.java:314)

at java.base / java.util.concurrent.CompletableFuture.completeThrowable (CompletableFuture.java:319)

at java.base / java.util.concurrent.CompletableFuture $ UniCompose.tryFire (CompletableFuture.java:1081)

at java.base / java.util.concurrent.CompletableFuture $ Completion.run (CompletableFuture.java:478)

at net.minecraft.server.v1_16_R3.ChunkTaskQueueSorter.b (SourceFile: 58)

at net.minecraft.server.v1_16_R3.ThreadedMailbox.e (ThreadedMailbox.java:91)

at net.minecraft.server.v1_16_R3.ThreadedMailbox.a (ThreadedMailbox.java:138)

at net.minecraft.server.v1_16_R3.ThreadedMailbox.run (ThreadedMailbox.java:103)

at java.base / java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1128)

at java.base / java.util.concurrent.ThreadPoolExecutor $ Worker.run (ThreadPoolExecutor.java:628)

at java.base / java.lang.Thread.run (Thread.java:829)

Caused by: net.minecraft.server.v1_16_R3.ReportedException: Exception generating new chunk

at net.minecraft.server.v1_16_R3.PlayerChunkMap.lambda $ null $ 39 (PlayerChunkMap.java:1290)

at com.mojang.datafixers.util.Either $ Left.map (Either.java:38)

at net.minecraft.server.v1_16_R3.PlayerChunkMap.lambda $ b $ 41 (PlayerChunkMap.java:1275)

at java.base / java.util.concurrent.CompletableFuture $ UniCompose.tryFire (CompletableFuture.java:1072)

… 8 more

Caused by: java.lang.IllegalStateException: zip file closed

at java.base / java.util.zip.ZipFile.ensureOpen (ZipFile.java:920)

at java.base / java.util.zip.ZipFile.getEntry (ZipFile.java:347)

at java.base / java.util.zip.ZipFile $ 1.getEntry (ZipFile.java:1126)

at java.base / java.util.jar.JarFile.getEntry0 (JarFile.java:578)

at java.base / java.util.jar.JarFile.getEntry (JarFile.java:508)

at java.base / java.util.jar.JarFile.getJarEntry (JarFile.java:470)

at org.bukkit.plugin.java.PluginClassLoader.findClass (PluginClassLoader.java:144)

at org.bukkit.plugin.java.JavaPluginLoader.getClassByName (JavaPluginLoader.java:216)

at org.bukkit.plugin.java.PluginClassLoader.findClass (PluginClassLoader.java:122)

at org.bukkit.plugin.java.PluginClassLoader.findClass (PluginClassLoader.java:111)

at java.base / java.lang.ClassLoader.loadClass (ClassLoader.java:589)

at java.base / java.lang.ClassLoader.loadClass (ClassLoader.java:522)

at com.plotsquared.bukkit.generator.BukkitPlotGenerator.generateChunkData (BukkitPlotGenerator.java:169)

net.minecraft.server.v1_16_R3.PlayerChunkMap.lambda $ null $ 39 (PlayerChunkMap.java:1277)

Reinstall the server with the correct Minecraft version.

Looks like you got the wrong one. But it could also be that you have the wrong Java version on your server.

What do you mean by real Minecraft version? Java version: openjdk version "11.0.11" 2021-04-20