I am trying to proceed with the game after the event, but whenever I go to the battle page it displays the boss fight, but the boss is gone, so basically there's just my Sylesti alone, and I am supposed to fight the invisible boss... help?

@Elea17

Try going here http://www.sylestia.com/explore/zone/?zone=esiorshaven

See if that fixes it.

I tried, but the problem is not the map, i can access it, but when I click on the cavern all I can see is my sylesti alone, battling the grinchness which is not there... I can't do anything now, everytime I try to give a potion, or change sylesti, it says that I can't do it during a battle.

@Elea17

This should be working now.

Visit here: http://www.sylestia.com/explore/zone/?zone=esiorshaven

It will kick you out of your battle and redirect you to the World Map since the event is over and that zone is closed atm.

I just tested it for myself, so it should work. There was a small error that was preventing it from working properly.

It worked! Thank you very much

You're welcome. Sorry for the long delay.