1. After the game is fully installed and patched (AKA once you start getting the error), exit the launcher

2. Go to the game's folder (usually C:\Program Files (x86)\Steam\steamapps\common\Ragnarok), and either rename Ragexe.exe to Ragexe.exe.bak, or delete it

3. Go to https://choobs.org/stuff/patch.php , set the server to Chaos (Renewal), and the patch number to 4763 (4742 if yer also getting sprite errors)

4. Click Download, and overwrite the patch.inf in the game's folder with it

5. Relaunch the game, it should finally update normally and give you the proper launcher

6. Have fun! If the resolution is messed up or something, you can tweak the settings by launching Setup.exe, once again in the game's folder