During the event, I was in the middle of fighting a bandit, and when I hit the "End Turn" button, I was logged out and taken back to the home screen.
This has happened once before, but I didn't report it the first time because I thought I must have done it by accident, but this time I'm certain it wasn't my fault.
I haven't done a lot of battling outside of events lately, so unfortunately I'm not sure if this is a problem with battles in general or is specific to raids.

@Katasaur,

A million things could cause this and it would be near impossible for me to figure out which it is, but it has nothing to do with battling.

It also just could have been an expiration of your session. All sessions expire after 2 weeks from your last log in.

But this is a fairly rare occurrence and it's easy to just log back in so unfortunately, unless I stumble across it, there isn't much I can feasibly do.

Alright, thanks for responding. It's not that big of a deal, just thought I should mention it in case it was a problem.
I don't think it was the session ending though because the last time it happened was just a couple of days ago.

Yea. Then it could just be anything.

We use session id's which are checked and change on every page load. If the id's don't match, you get kicked out. This is to prevent various forms of hacking and exploits. It's very possible that just every once in awhile something goes screwy, the server thinks your id's don't match, and it kicks you out.

It's also possible it's a browser issue where sometimes they don't pass on the session properly which again will cause you to be logged out.

Basically, when logged into Sylestia, every page load you do you're logged out. It then checks to see if you're valid to be re-logged in. So if something happens with that re-log in part, you'll just stay logged out.

And it could be tons of things that could be causing it and near impossible to figure out what unless someone is able to duplicate the log out issue with 100% accuracy. But after a year of using this system, I've yet to figure out a way to duplicate it. Just happens randomly it seems.