[14:39:23] [Server thread/INFO]: Starting minecraft server version 1.12.2
[14:40:33] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from RFTools Dimensions (rftoolsdim)

Caused by: java.lang.IllegalStateException: This is not a JSON Array.
at com.google.gson.JsonElement.getAsJsonArray(JsonElement.java:106) ~[JsonElement.class:?]
at mcjty.rftoolsdim.config.DimletRules.readRulesFromFile(DimletRules.java:146) ~[DimletRules.class:?]
at mcjty.rftoolsdim.config.DimletRules.readRulesFromFile(DimletRules.java:134) ~[DimletRules.class:?]
at mcjty.rftoolsdim.config.DimletRules.readRules(DimletRules.java:89) ~[DimletRules.class:?]
at mcjty.rftoolsdim.proxy.CommonProxy.preInit(CommonProxy.java:47) ~[CommonProxy.class:?]
at mcjty.rftoolsdim.proxy.ServerProxy.preInit(ServerProxy.java:12) ~[ServerProxy.class:?]
at mcjty.rftoolsdim.RFToolsDim.preInit(RFToolsDim.java:91) ~[RFToolsDim.class:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_101]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_101]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_101]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_101]
at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:606) ~[ftbserver.jar:?]
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_101]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_101]
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:253) ~[ftbserver.jar:?]
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:231) ~[ftbserver.jar:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_101]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_101]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_101]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_101]
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) ~[minecraft_server.1.12.2.jar:?]
at com.google.common.eventbus.EventBus.post(EventBus.java:217) ~[minecraft_server.1.12.2.jar:?]
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:148) ~[LoadController.class:?]
at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:602) ~[Loader.class:?]
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98) ~[FMLServerHandler.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:331) ~[FMLCommonHandler.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125) ~[nz.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_101]
[14:40:33] [Server thread/ERROR]: This crash report has been saved to: /games/ni832873_1/ftproot/minecraftftb/./crash-reports/crash-2018-01-28_14.40.33-server.txt
[14:40:33] [Server thread/INFO]: Stopping server
[14:40:33] [Server thread/INFO]: Saving worlds
[14:40:33] [Server Shutdown Thread/INFO]: Stopping server
[14:40:33] [Server Shutdown Thread/INFO]: Saving worlds

You made a mistake editing your dimlets.json file. Pastebin the whole thing. If you didn't edit it, then it got corrupted. In that case, just delete it and a new one will be generated. But more importantly, where's the log of the crash before this started happening?

Well after you mentioned corruption I looked into the logs and noticed that the server ran out of allowed storage space because of the FTB backups every hour causing the server to crash and preventing the .json file from saving the data properly.

I will delete the backups and replace my config folder from a backup and see if we get somewhere

Deleting the backups and restoring the config folder fixed the problem. Thank you for pointing me in the right direction.