When trying connect via steam launcher script.

If you got these error messages when trying launch the game, just copy ( or cut) addons folder from Arma2 folder and paste it in arma 2 OA folder.

first

and second message

Check Addons folder.
8.21Gb, 162 files
Try del origins folder and copy new.

†Maniac† wrote:Check Addons folder.
8.21Gb, 162 files
Try del origins folder and copy new.

This^
Many people forget to copy over the Addons folder from their ARMA 2 folder to their ARMA 2 Operation Arrowhead folder, or just make a junction if you do not have space to do so.