When I try to start the game it crashes instantly.

Crash-Info:

The game crashed whilst initializing game
Error: com.google.gson.JsonParseException: com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Invalid escape sequence at line 4 column 30 path $.pack.description

Log:

[11:22:56] [Client thread/INFO]: Setting user: RedLukasMc
[11:22:58] [Client thread/WARN]: Skipping bad option: streamPreferredServer:
[11:22:58] [Client thread/INFO]: LWJGL Version: 3.1.2 build 29

I will now try to update my Java to a newer version, however I don't think that will fix the bug...