I am not sure what’s causing this. Panda3D’s error messages are not terribly precise when it comes to intervals or sequences. But I notice a few things in your code:
I am not sure if it’s a good idea to give your interval a name. That makes the interval unique. If an interval with the same name is started, the old one finishes automatically. Calling finish on that old interval might produce errors.
You set other to be self.avatar, which is also the node that the interval performes on. That makes the interval relative to itself, which is not recommended (see the manual).
You are requesting a new state directly (request(“Stand”). Maybe you are using the old FSM instead of the new one? With the new one it would be something like request(“to_stand”) and then you would use the filter function of your current state to determine if to go to the “Stand” state.
When you call finish() (instead of pause()), it finishes the sequence meaning that it also calls the Func at the end, so it calls self.request(‘Stand’) while you’re still in exitAdvance. I’m not sure, but I don’t think it’s valid to change states in an FSM exit method.