Hi ceematt,
Sorry this response took so long. That error usually displays when the web form code has been changed and some pertinent code was either modified or removed. Is this still happening now? If you were to create a brand new web form and use the code provided by Method, without modifying it, then host it and submit some dummy data, do you receive this message? I'm unable to replicate this error with the stock code.
If you're just looking to add leads to Method from another system, you can utilize the MethodAPI.
- Ashur