How to patch Reported Properties using HTTPS

Hello Peter Tran,

It sounds like you're running into an issue with patching the reported properties of your IoT device's device twin. From what you've described, the error you're seeing about tags and desired properties being null might indicate that the request body you're sending to the IoT Hub doesn't have the expected structure.

When you want to patch reported properties, you need to ensure that your request includes the reported properties you want to update without setting the entire tags or desired properties to null. You're correct that using a PUT request would replace the entire device twin, which is not what you want to do.

Here's a general approach you can take to resolve this:

1. Correct Use of PATCH vs PUT: You're absolutely right to avoid using a PUT request—it would overwrite the entire twin, including desired and tags sections, potentially setting them to null if not included.
2. Proper PATCH Structure for Reported Properties: When using HTTPS to patch reported properties, your request body must be structured like this:

{
  "properties": {
    "reported": {
      "firmware_version": "v1.1"
    }
  }
}

This ensures you're only updating the reported section without affecting desired or tags.

3. Validate Your Endpoint: Double-check that you're hitting the correct endpoint for your device twin update. It should look something like this:

      
      PATCH https://{your-iot-hub}.azure-devices.net/twins/{device-id}?api-version=2020-03-13
      
   

4. Use of Service Token: You're correct again—device tokens typically lack permission to update twin properties via HTTPS. A service token with the right RBAC roles (e.g., IoT Hub Data Contributor) is required.
5. Avoiding Null Tags and Desired Properties: If your PATCH body omits tags and desired, IoT Hub may interpret them as null unless explicitly preserved. To avoid this, either:
   • Include the current tags and desired values in the PATCH body, or
   • Use a minimal PATCH that only targets reported as shown above updates properly.

Ref Doc: https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-device-twins

Hope this helps!
Thank you!