Duplicate form but "VALIDATION_ERROR"

Dear Sirs

    I use typeform API, try to duplicate a existing form.

    Following API (https://www.typeform.com/developers/create/walkthroughs/).

    get existing form, copy the form , remove the id. but get problem in posting…

    get the error “VALIDATION_ERROR”

The whole payload is copied from existing form.

What’s kind of errors I missing ?

THank you very much!

{
    "code": "VALIDATION_ERROR",
    "description": "The payload is invalid.",
    "details": [
        {
            "code": "NOT_ALLOWED_PROPERTY",
            "description": "should NOT have additional properties",
            "field": "/url",
            "in": "body"
        },
        {
            "code": "NOT_ALLOWED_PROPERTY",
            "description": "should NOT have additional properties",
            "field": "/status",
            "in": "body"
        },
        {
            "code": "NOT_ALLOWED_PROPERTY",
            "description": "should NOT have additional properties",
            "field": "/contentType",
            "in": "body"
        },
        {
            "code": "NOT_ALLOWED_PROPERTY",
            "description": "should NOT have additional properties",
            "field": "/body",
            "in": "body"
        },
        {
            "code": "REQUIRED_PROPERTY",
            "description": "should have required property 'title'",
            "field": "/title",
            "in": "body"
        }
    ]
}