At net.minecraftforge.fml.common.Loader.sortModList (Loader.java:298) ~ [Loader.class:?]
at net.minecraftforge.fml.common.Loader.loadMods (Loader.java:570) ~ [Loader.class:?]
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading (FMLServerHandler.java:98) ~ [FMLServerHandler.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart (FMLCommonHandler.java:333) ~ [FMLCommonHandler.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b (DedicatedServer.java:125) ~ [nz.class:?]
at net.minecraft.server.MinecraftServer.run (MinecraftServer.java:486) [MinecraftServer.class:?]
at java.lang.Thread.run (Thread.java:748) [?: 1.8.0_151]
[39; 0m>
[K [31; 1m [21:36:15] [Server thread / ERROR] [minecraft / MinecraftServer]: This crash report has been saved to: /mnt/./crash-reports/crash-2019-02-01_21. 36.15-server.txt
That's the crash report.
Looks like you have a mod installed that needs another mod to run.