An online multiplayer mod for Nuclear Throne. · By YellowAfterlife
Try moving NTT into a directory without spaces/non-English characters in the path.
I'm running into this problem as well and I got my copy off steam. I'm not sure what you mean by directory, like is it file directory or something else because my friend has the same path to the game files as me and his works.
WHY TO THE REPAIR THIS PROBLEM