q: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
a: you're most likely using an old version of Optifine, update it.
q: java.lang.NoSuchFieldError: ofAaLevel
a: you're most likely using an version of Optifine made for a newer version of minecraft, we're still on 1.10.0
q: when i join a world my game freezes and i get kicked!
a: its the game downloading and/or turning on the wynncraft's resourcepack which makes it reload all assets, that often is heavy on your computer. try assigning more RAM to minecraft or turn off some background apps.
q: i crash when i start my game. what to do?
a: first try to google the problem, if that doesnt help check if someone hasnt already asked about it on our forum post, and as a last effort post a question about it on our forum post found here