ERROR message when I try to start sponge server with plugin projectworlds and plugin projectcore [Solved]

my problem (as the title describes) is when I try to run my server. This error only happens when I try to run the server with the plugins. It doesn´t matter if I have mods on my server or not. Also I am playing on the version 1.8.
I would be really happy for an answer.

Here is the crash report:
---- Minecraft Crash Report ----

WARNING: coremods are present:
SpongeCoremod (spongeforge-1.8-1521-2.1-DEV-729.jar)
Contact their authors BEFORE contacting forge

// You should try our sister game, Minceraft!

Time: 08.03.18 19:11
Description: Exception in server tick loop

java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String
at org.spongepowered.mod.plugin.SpongeModPluginContainer.getSortingRules(
at net.minecraftforge.fml.common.Loader.sortModList(
at net.minecraftforge.fml.common.Loader.loadMods(
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(
at Source)

A detailed walkthrough of the error, its code path and all known details is as follows:

– System Details –
Minecraft Version: 1.8
Operating System: Windows 10 (x86) version 10.0
Java Version: 1.8.0_161, Oracle Corporation
Java VM Version: Java HotSpot™ Client VM (mixed mode), Oracle Corporation
Memory: 34756824 bytes (33 MB) / 156372992 bytes (149 MB) up to 259522560 bytes (247 MB)
JVM Flags: 0 total;
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP v9.10 FML v8.0.99.99 Minecraft Forge 11 mods loaded, 11 mods active
States: ‘U’ = Unloaded ‘L’ = Loaded ‘C’ = Constructed ‘H’ = Pre-initialized ‘I’ = Initialized ‘J’ = Post-initialized ‘A’ = Available ‘D’ = Disabled ‘E’ = Errored
U mcp{9.05} [Minecraft Coder Pack] (minecraft.jar)
U FML{} [Forge Mod Loader] (forge-1.8-
U Forge{} [Minecraft Forge] (forge-1.8-
U Sponge{1.8-1521-2.1-DEV-729} [SpongeForge] (minecraft.jar)
U ArchitectureCraft{1.2.1} [ArchitectureCraft] (ArchitectureCraft-1.2.1-mc1.8.jar)
U CustomSpawner{3.4.0} [DrZhark’s CustomSpawner] (CustomMobSpawner+3.4.0.jar)
U customnpcs{1.8.0_beta} [CustomNPCs] (CustomNPCs_1.8.0_beta.jar)
U MoCreatures{8.0.1} [DrZhark’s Mo’Creatures Mod] (Mo-Creatures-Mod-1.8.8.jar)
U pjc{0.2.1} [ProjectCore] (projectcore-7.0.0-0.2.1.jar)
U pjw{0.12.0} [ProjectWorlds] (projectworlds-7.0.0-0.12.0.jar)
U SimpleDimensions{1.1} [Simple Dimensions] (SimpleDimensions-1.1.jar)
Loaded coremods (and transformers):
SpongeCoremod (spongeforge-1.8-1521-2.1-DEV-729.jar)

Profiler Position: N/A (disabled)
Is Modded: Definitely; Server brand changed to 'fml,forge,SpongeForge'
Type: Dedicated Server (map_server.txt)

1.8 builds of Sponge are no longer supported, it is recommended that you update to a later version, at least 1.10.2.

Also when posting crash reports, please use a service such as Gist or Pastebin.

I am sorry I could not help with your error.

~ Alice

ok. Thank you very much.