can't even open the game xD

[GM-Pandora]

Make sure you don't have a data folder.

Basically this error is saying that it's not finding this file. This file is in our hero.grf

data.ini is what tells the client what to read, which is why it should contain:

[Data]
0=heRO.grf -> our server patch
1=sdata.grf -> Gravity file
2=data.grf -> Gravity file

This tells your client, check the server patch first, then RO's files.

However, it will always look in the "data" folder first, which is why if you have one, remove or rename it.