Anyone who was using modded files as well as people who have not modded any files are having the annoying corrupted file problems again. And Enmasse says you should replace the game.version file then repair the client to fix it. But this does not fix the issue for many people instead when they zone into the actual raid they crash and are unable to log back in. This is very annoying making it unplayable for many people.
And because of this some of my own guild was having problems joining our raid for Kelsaik. So what I did was I compiled a patch which includes all of the packed files which came in this update this way if you have tried everything and are at the point that you are thinking of uninstalling the game and re-downloading it all over you could try this patch i made which will directly patch all of the files modified during this update. Keep in mind it replaces all of the korean modded files and I'm not sure if there's a new Ktera update for them yet or whether its safe to patch them back again I'll find that out and update this in the future and provide more information. But if your using a 64bit operating system you will want to use this installer: https://docs.google.com/file/d/0BwGeHg1m4YFLWnNrMnNzbU05dkk/edit?usp=sharing
I was going to make a installer for 32bit as well but because of the large file size I decided to just provide you with a manual patch since you can just extract it into the Tera folder which should be easy. Which you can download from here https://docs.google.com/file/d/0B90u9z2fsJ4bcUplb3RwWEtZVGM/edit?usp=sharing
Hopefully this will make you able to login and play properly with it. I know I was able to login and do the 10man fine without any crashing. And it was a lot of fun hopefully you get to enjoy playing them too!
Update: It seems I missed patching the newer Tera.exe file which goes along with it so in worst case use the patch above then use the repair and it should upgrade that one file without you having to uninstall and reinstall. One of my friends said this saved her when she was able to uninstall the whole game so it will be beneficial to use.