[BUG] ERR Could not connect to MQTT. error="invalid topic prefix"

[psiho]

Go Hass Agent Version
v11.0.0

Describe the bug
On two separate machines, fresh first install and config of MQTT, I get error: Could not connect to MQTT. error="invalid topic prefix", and agent is not visible in Hass MQTT integration.

To Reproduce
Steps to reproduce the behaviour:

1. Install using Arch AUR
2. Config on initial run
3. run from terminal to see output... above error is displayed and HASS MQTT integration does not have agent
4. Check MQTT server log... no logged attempts to login
5. Enter any other (false) address of MQTT server... same thing

Expected behaviour
I'd expect a successful connect to MQTT or at least different error message. Because, entering completely wrong MQTT server in config produces the same error.

Logs

1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_reboot/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_suspend/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_hibernate/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_poweroff/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_start_camera/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/button/go_hass_agent/_stop_camera/press
1:47PM DBG Adding subscription for topic. topic=homeassistant/number/go_hass_agent/_volume/set
1:47PM DBG Adding subscription for topic. topic=homeassistant/switch/go_hass_agent/_mute/set
1:47PM DBG Adding subscription for topic. topic=gohassagent//dbuscommand
1:47PM ERR Could not connect to MQTT. error="invalid topic prefix"

Desktop (please complete the following information):

• OS: Linux
• Distribution: Arch

[psiho]

After setting topic_prefix manually in the config, I'm getting another error. There is not "topic_prefix" in GUI config. I don't see in docs, so it's a bit confusing.

Anyway, new error is now more descriptive: ERR Error establishing MQTT connection. error="failed to connect to tcp://192.168.1.9:1883: EOF"

MQTT now logs attempot to conenct with Invalid protocol version 5 in CONNECT from 192.168.1.34.
... so I guess it's clear now, although I think this requirement for MQTT protocol v5 (and the above config too) should be more clear in the docs.

[joshuar]

Hey thanks for reporting, I believe this is the same problem as #375. I've issued a patch release to fix it, see my comment on the issue. You've figured out the workaround though, so you shouldn't need to do the re-register step I've mentioned after upgrading.

Thanks for the note on the MQTT v5 requirement. That wasn't intentional but is unfortunately due to the underlying library used for MQTT connectivity. I'll add a note in the README.