got the same thing
tells me my version is pirated though I've owned the game for years, then gives the same exception after having steam validate the files. I get not wanting to support pirates but has to be a better way, going this far is everything thats wrong with DRM as it ruins the experience for people that actually own the game, as you can see I do in fact own terraria and the original modloader picks it up just fine so it is properly installed though I wonder if having it installed on a game drive would be an issue.
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