Hi @RaysApps,

The only possible return codes from this function are:

1. NX_AZURE_IOT_SUCCESS = 0
2. NX_AZURE_IOT_SDK_CORE_ERROR = 0x2001
3. NX_AZURE_IOT_INVALID_PARAMETER = 0x2002

I'm wondering if you are truncating the return and you actually seeing a NX_AZURE_IOT_SDK_CORE_ERROR.

Moving onto this specific error, unfortunately the NetXDuo SDK swallows the errors from the underlying JSON library and returns a generic code which makes it less than useful.

The best approach here would be to set a breakpoint when calling that function and then step through until you hit the error in the underlying json library.

You will probably end up in this function. Most likely the issue is going to be that there wasn't enough space in the buffer. I would try and estimate the size of the buffer you would need and make sure you have allocated enough space.

Hi @ryanwinter, I was able to debug through the function you mentioned and found that the required buffer for the telemetry data is exceeding the allocated length. The buffer size allocated is equal to the '#define TELEMETRY_BUFFER_SIZE 256' value in 'azure_iot_nx_client.c' file. Updating the TELEMETRY_BUFFER_SIZE to 512 resolved this issue. Thank you for your helpful suggestion.