It seems there's some conflict going on.

I'm using a callback script for myFirstParameter that calls myFunction(parm) in the Python Module.
the callback script goes like: The problem seems to arise when you create a new parameter and forget to register its name, Houdini by default would call it “parm”.
When you later update the new parameter with a custom name “mySecondParameter”, Houdini seems to automatically update the callback script function in the very first parameter. Now the callback is:
And when you use myFirstParameter you would get the error: Error running callback: Traceback (most recent call last):
File “<stdin>”, line 1, in <module> KeyError: ('mySecondParameter',)


Does it look like a bug or is that the natural behavior of how things should go?
Can you reproduce it?

It's logged as bug #94685

It's a problem easy to fix when you know how it happens otherwise you could be puzzled a bit.
A good practice is to never leave a new parm registered with the default “parm” name, especially if you are using callback scripts with kwargs.
I know it can happen especially when you are testing a lot of parameters, so be aware that if you get a KeyError and you know you have a callbackscript with kwargs, review the callback and sees if it has changed.

if you want to see this behavior in action have a look at the file, and see if you can reproduce it (just by changing the name of the default parm)