Error 422 Unprocessable Entity - API Update Dashboard

I am trying to update a dashboard via API call. When I POST using postman, I get the error 422 Unprocessable Entity and the below output:

“fieldNames”: [
“classification”: “RequiredError”,
“message”: “Required”

I have google it but I could not find any info as well as in API Docs. Any idea?

The problem was that the payload type (was not specified)

I guess this probably answers your question: How create Dashboard and Panel via API