Trying to update booking via api explorer yields error

Questions
1

Hi, I need to move bookings in bulk from a departing staff member to a newly hired one. So, I thought to use the update booking api, and try this out using the API Explorer. I’m using the Node.js api if that matters. The booking id is a parameter to the api call. The update PUT looks like:

{
    booking: {
      appointmentSegments: [
        {
          durationMinutes: 180,
          serviceVariationId: 'LFYUN_redacted_COAZNN2IYQMH2O',
          teamMemberId: 'TM5f_redacted_coSnz',
          serviceVariationVersion: 1_redacted_274
        }
      ]
    }

and the resultant error looks like:

{
  "errors": [
    {
      "field": "booking",
      "detail": "No valid changes",
      "code": "BAD_REQUEST"
    }
  ]
}

I’m sure I don’t understand the error message. What am I doing wrong that this doesn’t work to update the initial appointment segment?

Chris