How to resolve MQTT CONNACK error 5 - Connection Refused, not authorized

Question

I am using the Azure IoT SDK on an IoT device and trying to connect to the IoT Hub. the embedtls connection setup is successful, the tsl/ssl handshake is successful, but the MQTT Connect packet returns a CONNACK with error 5 - Connection Refused, not authorized. Please assist.

Answer 1

Hi @Brad Johnson I'm glad that you were able to resolve your issue and thank you for letting us know your solution so that others experiencing the same thing can easily reference this! I'll repost your solution in case you'd like to accept the answer .

Error Message:

MQTT Connect packet returns a CONNACK with error 5 - Connection Refused, not authorized

Issue:

Using Azure RTOS middleware to connect to Azure IoT Hub through MQTT. The embedtls connection setup is successful, the tsl/ssl handshake is successful, but the MQTT Connect packet returns a CONNACK with error 5 - Connection Refused, not authorized

Solution:

There is a type-casting error in the code which led to truncated connection data within the Azure IOT freeRTOS middleware.

If I missed anything please let me know and I'd be happy to add it to my answer, or feel free to comment below with any additional information on the specific section of the code which you have updated to resolve this.

I hope this helps!

If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.

Answer 2

Hello @Brad Johnson ,

the Azure IoT Hub supports devices to connect using several SDKs and using 'plain' MQTT.

Using the SDKs is recommended due to extra logic being implemented already like throttling and reconnecting.

The MQTT connection is very particular regarding the topics being used.

Please compare your MQTT calls with this reference solution written in C#.

Remember to supply the correct certificate (the Baltimore certificate is deprecated. You need to supply a DigiCert certificate now).

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