Valve Patches Decade Old Team Fortress 2 Bug

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Valve has quietly released a patch fixing a bug in Team Fortress 2 that has existed since 2007, that's a decade old bug. And it was not benign. The bug caused hit detection issues, so that the client and server hit boxes fell out of sync. It was reported by Reddit user sigsegv_ who explains:

Basically, merely by changing class, pose parameters could get seriously screwed up, messing up how the hitboxes animate on the server side (which, in turn, messes up hit detection).

The human player models mostly just had messed up leg animations (but also issues with e.g. heads leaning the wrong way when moving), because only the move_x and move_y pose parameters got swapped. The MvM robot player models have, uh, slightly more different permutations of pose parameters, so the consequences there were much greater in many cases for them.

He also made a video demonstrating the bug that you can see below. It's quite apparent. You can see that the bug was rectified in the latest TF2 patch notes, but it's given a discreet description: "Fixed an animation bug that would cause the client and server hitboxes to become out of sync."

At least the bug is fixed, but it shows you how some errors can go unnoticed for a long... long time.