I got that error, not long back, when I used a ML model from out of the box package and directly published without training it.
There are a few post on the forum for the error but only one has a solution. I am sure you have gone through them.
Are you using the generic ML model from Out of the Box package?
If so, you need to retrain the model to get the ML model incorporate settings that are specific to your project. This training generates the set of files that are considered as the ml model configuration for one project.
you may provide more information on the ML skill you are using and how have you incorporated it.
I also suggest you to retrain after updating the packages, as that would eliminate any error from old/depreciated/error-prone packages
Also, if it is related to Document Understanding then I think the master @Lahiru.Fernando can advise something.