I CANT LAUNCH MINECRAFT 1.8

HELP! I GET THIS ERROR MESSAGE!
[09:39] [Client thread/INFO]: Setting user: bearbaugh
[09:39] [Client thread/INFO]: (Session ID is token:e12382fe09104666b245fbf1e3473d59:66d746210d2b4e069ac8f79028a3dd38)
Exception in thread "Client thread" com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Expected ':' at line 1 column 12290
at com.google.gson.internal.Streams.parse(Streams.java:56)
at com.google.gson.TreeTypeAdapter.read(TreeTypeAdapter.java:54)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.fromJson(Gson.java:803)
at com.google.gson.Gson.fromJson(Gson.java:768)
at ry.b(SourceFile:148)
at ry.<init>(SourceFile:42)
at net.minecraft.server.MinecraftServer.<init>(SourceFile:155)
at cyk.<init>(SourceFile:40)
at bsu.<init>(SourceFile:282)
at net.minecraft.client.main.Main.main(SourceFile:120)
Caused by: com.google.gson.stream.MalformedJsonException: Expected ':' at line 1 column 12290
at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1505)
at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:519)
at com.google.gson.stream.JsonReader.peek(JsonReader.java:414)
at com.google.gson.internal.bind.TypeAdapters$25.read(TypeAdapters.java:644)
at com.google.gson.internal.bind.TypeAdapters$25.read(TypeAdapters.java:667)
at com.google.gson.internal.bind.TypeAdapters$25.read(TypeAdapters.java:642)
at com.google.gson.internal.Streams.parse(Streams.java:44)
... 12 more
Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release