Hi, I have a trouble when modifying the header of a request. The header modify rules only take effect in the first tab group. I am not sure but I don't think it should return in the loop as following: https://github.com/kylepaulsen/ResourceOverride/blob/f19d8bf6d9409e3a693c266d67827078506594a7/src/background/headerHandling.js#L113 A temporary workaround is simple: put all header rules in the first tab group.