With that being said, I do not know if you can join a friend's session WHILE using the trainer. When I joined my friend, I was not using the trainer, nor copied over the cracked EAC.exe, so I'm hoping today I can test the theory out if it will let us play together.
I just tried it out; everything still seems to work fine for me. Did you follow the instructions and activate the trainer before continuing past the screen with the big planet, "Outriders," and "[Space] To Continue"?
Failing to to that is the only way I've managed to get that error.
[Edited by samuelsghost, 4/3/2021 10:41:36 AM]
Follow the instructions in the 1st post.