umqtt/simple (connect)

Trying to run an example, came by: https://github.com/GoogleCloudPlatform/iot-core-micropython

It stops here:

Creating JWT...
Sending message with password eyJ0eXAiOiAiSl
[...] JWId1Qjmb4BjjKHPLITppMbzo1FDBigdmqmw_CwUQXjB2mUyRX8QcUw6ApvZTP98yfrc7gP0lc5eQmVZR0xsSmBlJM_iGJp1vJhkwirpIeXgnILO9w==
Traceback (most recent call last):
File "main.py", line 190, in
File "main.py", line 170, in get_mqtt_client
File "umqtt/simple.py", line 97, in connect
IndexError: bytes index out of range
MicroPython v1.12 on 2019-12-20; ESP32 module with ESP32

and can't conclude de connection, any suggestion of what can be?

follow line 190 in main.py:

client = get_mqtt_client(config.google_cloud_config['project_id'], config.google_cloud_config['cloud_region'], config.google_cloud_config['registry_id'], config.google_cloud_config['device_id'], jwt)

I think the problem is about umqtt/simple.py

Start with umqtt/simple.py line 97 and the get_mqtt_client call at main.py lines 170 and 190. Reproduce the connection attempt on MicroPython v1.12 with the ESP32 example, then trace the bytes index error. Done means the example completes the MQTT connection without the exception, with the cause and verification captured.