Updating a Quote Returns Error ""Please provide a valid Status Code""

I'm updating an existing Quote in Xero and I get the following Validation Error: "Please provide a valid Status Code"

You will get this error when updating a DRAFT status Quote without changing the status. To update the content of a DRAFT Quote without changing the status you will need to exclude the status field from the JSON that is upload to Xero by removing this line from the $json variable:

["Status" ; Quotes::Status; JSONString];