net.minecraft.class_148: Exception loading chunk
at knot/net.minecraft.class_9761.method_60462(class_9761.java:104) ~[server-intermediary.jar:?]
at java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:934) ~[?:?]
at java.base/java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:911) ~[?:?]
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[?:?]
at java.base/java.util.concurrent.CompletableFuture.postFire(CompletableFuture.java:614) ~[?:?]
at java.base/java.util.concurrent.CompletableFuture$UniExceptionally.tryFire(CompletableFuture.java:977) ~[?:?]
at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482) ~[?:?]
at knot/net.minecraft.class_1255.method_18859(class_1255.java:164) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_3215$class_4212.method_18859(class_3215.java:620) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1255.method_16075(class_1255.java:138) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_3215$class_4212.method_16075(class_3215.java:629) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_3215.method_19492(class_3215.java:282) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.MinecraftServer.method_20415(MinecraftServer.java:870) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.MinecraftServer.method_16075(MinecraftServer.java:858) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1255.method_5383(class_1255.java:123) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.MinecraftServer.method_16208(MinecraftServer.java:826) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:712) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:290) ~[server-intermediary.jar:?]
at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]
Caused by: java.lang.NoSuchMethodError: 'java.lang.String net.minecraft.class_2487.method_10558(java.lang.String)'
at knot/com.tristankechlo.explorations.worldgen.structures.pieces.SlimeCaveStructurePiece.lambda$new$0(SlimeCaveStructurePiece.java:40) ~[explorations-fabric-1.21.4-1.6.2.jar:?]
at knot/net.minecraft.class_3470.(class_3470.java:60) ~[server-intermediary.jar:?]
at knot/com.tristankechlo.explorations.worldgen.structures.pieces.SlimeCaveStructurePiece.(SlimeCaveStructurePiece.java:40) ~[explorations-fabric-1.21.4-1.6.2.jar:?]
at knot/com.tristankechlo.explorations.worldgen.structures.pieces.SlimeCaveStructurePiece.(SlimeCaveStructurePiece.java:45) ~[explorations-fabric-1.21.4-1.6.2.jar:?]
at knot/net.minecraft.class_6624.method_38711(class_6624.java:73) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_3449.method_41621(class_3449.java:66) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2852.method_12392(class_2852.java:573) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2852.method_12395(class_2852.java:303) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_3898.method_43375(class_3898.java:586) ~[server-intermediary.jar:?]
at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:646) ~[?:?]
... 13 more
[00:19:55] [Server thread/ERROR]: This crash report has been saved to: C:\Users\danyl\Desktop\Minecraft Servers\Distant\crash-reports\crash-2025-05-14_00.19.55-server.txt
[00:19:55] [Netty Server IO #2/INFO]: Player [RadiALo] disconnected.

Minecraft version 1.21.5

This appears to be caused by a mod made for the wrong version. Download one specifically made for 1.21.5.