Note: Symptoms You see the error 409002 LinkCreationConflict in logs along with device disconnection or cloud-to-device message failure. Cause Generally, this error happens when IoT Hub detects a client has more than one connection. In fact, when a new connection request arrives for a device with an existing connection, IoT Hub closes the existing connection with this error. Reference: https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-troubleshoot-error-409002-linkcreationconflict#symptoms https://devblogs.microsoft.com/iotdev/understand-different-connection-strings-in-azure-iot-hub/