Problème de Serveur.

Bonjour,
Je me suis crée un serveur minecraft mais dès que je le lance il me met ça:

Code (cpp):

---- Minecraft Crash Report ----
// I let you down. Sorry :(

Time: 19/02/19 09:08
Description: Exception in server tick loop

java.net.UnknownHostException: mc300.dev.serv
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$2.lookupAllHostAddr(Unknown Source)
    at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getByName(Unknown Source)
    at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:166)
    at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:521)
    at java.lang.Thread.run(Unknown Source)


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

-- System Details --
Details:
    Minecraft Version: 1.12
    Operating System: Windows 7 (amd64) version 6.1
    Java Version: 1.8.0_171, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 79660984 bytes (75 MB) / 129761280 bytes (123 MB) up to 1038876672 bytes (990 MB)
    JVM Flags: 2 total; -Xincgc -Xmx1G
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    CraftBukkit Information:
   Running:
   Failed to handle CraftCrashReport:
java.lang.NullPointerException
    at org.bukkit.Bukkit.getName(Bukkit.java:92)
    at org.bukkit.craftbukkit.v1_12_R1.CraftCrashReport.call(CraftCrashReport.java:21)
    at net.minecraft.server.v1_12_R1.CrashReportSystemDetails.a(SourceFile:78)
    at net.minecraft.server.v1_12_R1.CrashReport.h(CrashReport.java:128)
    at net.minecraft.server.v1_12_R1.CrashReport.<init>(CrashReport.java:35)
    at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:571)
    at java.lang.Thread.run(Unknown Source)

    Profiler Position: N/A (disabled)
    Is Modded: ~~ERROR~~ NullPointerException: null
    Type: Dedicated Server (map_server.txt)