I started getting this issue on one of our entities while saving it.
This wasn’t the issue in CRM 3.0, this issue came up only after upgrading to CRM 4.0.
I was sure that the issue is because of some picklist getting filled up with dynamic options. But what was surprising was it was working perfectly fine in CRM 3.0.
After looking for it , i realized that the above error only comes in CRM 4.0, in CRM 3.0, it doesn’t throw error and we are also able to save the form.
So i thought of trying out these two options for correcting the error in CRM 4.0,
2) Than i thought of writing a plugin that on pre create or pre update event would remove the picklist field from being passed as an inputparameter to the CRM Platform. However the error showed up before we could even reach the pre-create plugin.
So finally added few options through customization section and on the onload removed that option using DeleteOption for the picklist. And than i was able to work with that picklist properly and was also able to solve the form