I didnt bothered reading all the posts but i'll post how i fixed error callback...
i wasnt playing from steam and i couldnt fix it so lets start
1) download and install steam. (http://store.steampowered.com/)
2) Copy your Ragnarok 2 client to X:\Program Files (x86)\Steam\SteamApps\Common\(your steam location might be different).
3) open steam and search for Ragnarok 2 on the store and start installing it... it will discover your files and download the corrupted/outdated files
4) after the update/fixing is done... go to your Ragnarok 2 folder and execute ro2client.exe (X:\Program Files (x86)\Steam\SteamApps\Common\Ragnarok Online 2\RO2Client.exe
5)enjoy it... if you ever have problems with future patches... just go to steam library... right click Ragnarok online 2>properties> Local Files then click Verify Files Integrity..
hope it helps... always fix the problems for me
by the way... dont try costumers support... they dont have a clue on how to fix many of the problems with their games... i was having problems with this error for 2-3 months till i found by myself the solution...
Edited by Itherian, 13 September 2013 - 06:47 AM.