So pretty much this is all the code from where it threw up the error.
25.05 01:17:32 [Server] Server thread/ERROR [FML]: Caught exception from sponge (SpongeForge)
25.05 01:17:32 [Server] INFO java.lang.AbstractMethodError: ninja.leaping.permissionsex.sponge.PEXSubjectData.setPermission(Ljava/util/Set;Ljava/lang/String;Lorg/spongepowered/api/util/Tristate;)Ljava/util/concurrent/CompletableFuture;
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerDefaultPermissions(SourceFile:1131) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerCommandsList(SourceFile:1142) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerLowPriorityCommands(SourceFile:1148) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at org.spongepowered.mod.SpongeMod.onServerAboutToStart(SpongeMod.java:388) ~[spongeforge-1.12.2-2655-7.1.0-BETA-3105.jar:1.12.2-2655-7.1.0-BETA-3105]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:278) ~[my.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:256) ~[my.jar:?]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.redirect$onPost$zza000(LoadController.java:560) [LoadController.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:148) [LoadController.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.Loader.serverAboutToStart(Loader.java:842) [Loader.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.FMLCommonHandler.handleServerAboutToStart(FMLCommonHandler.java:291) [FMLCommonHandler.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:268) [nz.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
25.05 01:17:32 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]
25.05 01:17:32 [Server] Server thread/ERROR [FML]: A fatal exception occurred during the server about to start event
25.05 01:17:32 [Server] INFO net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from SpongeForge (sponge)
25.05 01:17:32 [Server] INFO Caused by: java.lang.AbstractMethodError: ninja.leaping.permissionsex.sponge.PEXSubjectData.setPermission(Ljava/util/Set;Ljava/lang/String;Lorg/spongepowered/api/util/Tristate;)Ljava/util/concurrent/CompletableFuture;
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerDefaultPermissions(SourceFile:1131) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerCommandsList(SourceFile:1142) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.command.ServerCommandManager.registerLowPriorityCommands(SourceFile:1148) ~[dh.class:?]
25.05 01:17:32 [Server] INFO at org.spongepowered.mod.SpongeMod.onServerAboutToStart(SpongeMod.java:388) ~[spongeforge-1.12.2-2655-7.1.0-BETA-3105.jar:1.12.2-2655-7.1.0-BETA-3105]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:278) ~[my.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:256) ~[my.jar:?]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.redirect$onPost$zza000(LoadController.java:560) ~[LoadController.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:148) ~[LoadController.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.Loader.serverAboutToStart(Loader.java:842) [Loader.class:?]
25.05 01:17:32 [Server] INFO at net.minecraftforge.fml.common.FMLCommonHandler.handleServerAboutToStart(FMLCommonHandler.java:291) [FMLCommonHandler.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:268) [nz.class:?]
25.05 01:17:32 [Server] INFO at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
25.05 01:17:32 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]
please if you can help that would be amazing