Problem when launching server?

[17:48:43] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.util.ReportedException: Loading NBT data
at net.minecraft.nbt.NBTTagCompound.func_152449_a(NBTTagCompound.java:423) ~[dn.class:?]
at net.minecraft.nbt.NBTTagCompound.func_152446_a(NBTTagCompound.java:47) ~[dn.class:?]
at net.minecraft.nbt.NBTTagCompound.func_152449_a(NBTTagCompound.java:414) ~[dn.class:?]
at net.minecraft.nbt.NBTTagCompound.func_152446_a(NBTTagCompound.java:47) ~[dn.class:?]
at net.minecraft.nbt.CompressedStreamTools.func_152455_a(CompressedStreamTools.java:132) ~[dx.class:?]
at net.minecraft.nbt.CompressedStreamTools.func_152456_a(CompressedStreamTools.java:87) ~[dx.class:?]
at net.minecraft.nbt.CompressedStreamTools.func_74796_a(CompressedStreamTools.java:30) ~[dx.class:?]
at net.minecraft.server.MinecraftServer.registerExistingSpongeDimensions(MinecraftServer.java:481) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:334) ~[MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:254) ~[ko.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:441) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_66]
Caused by: java.io.EOFException: Unexpected end of ZLIB input stream
at java.util.zip.InflaterInputStream.fill(Unknown Source) ~[?:1.8.0_66]
at java.util.zip.InflaterInputStream.read(Unknown Source) ~[?:1.8.0_66]
at java.util.zip.GZIPInputStream.read(Unknown Source) ~[?:1.8.0_66]
at java.io.BufferedInputStream.read1(Unknown Source) ~[?:1.8.0_66]
at java.io.BufferedInputStream.read(Unknown Source) ~[?:1.8.0_66]
at java.io.DataInputStream.readFully(Unknown Source) ~[?:1.8.0_66]
at java.io.DataInputStream.readUTF(Unknown Source) ~[?:1.8.0_66]
at java.io.DataInputStream.readUTF(Unknown Source) ~[?:1.8.0_66]
at net.minecraft.nbt.NBTTagCompound.func_152448_b(NBTTagCompound.java:404) ~[dn.class:?]
at net.minecraft.nbt.NBTTagCompound.func_152446_a(NBTTagCompound.java:45) ~[dn.class:?]
at net.minecraft.nbt.NBTTagList.func_152446_a(SourceFile:66) ~[du.class:?]
at net.minecraft.nbt.NBTTagCompound.func_152449_a(NBTTagCompound.java:414) ~[dn.class:?]
… 11 more

problem solved, it was a mod i installed before!