Error setting up Google Nest integration

Third party integrations
1

Hi everyone,

I have tried to add the Google Nest integration to Home Assistant multiple times and I can’t seem to get it to work.

I followed these instructions carefully.

I have gone through FAQs and issues but nothing solves my problem.

This time, I compiled screenshots with:

  1. The settings I used when following the instructions above
  2. The error message I get back
  3. My Home Assistant version

It’s all in this Notion page.

I would really appreciate if someone could give me any hints as to why this is.

Thank you!

2

I finally managed to solve this. Here’s how for anyone interested!

There were two separate problems:

  1. The very first time I had tried to setup the integration, I used a different google account for the Nest Device Access Project (was using my personal gmail in one and my professional gmail in the the cloud project). I think that caused an issue with credentials. What I didn’t realise was that even after tryiung everything from scratch (creating a new GCP project, new Pub/Sub topic, etc) the OAuth 2 credentials from my first wrong attempt were still stored in Home Assistant. So I had to go to Application Credentials, see photo below, and manually remove the Nest credentials which were there.

    Screenshot 2025-02-13 at 10.11.02
    Screenshot 2025-02-13 at 10.11.021438×650 61.5 KB

  2. After this was done, the integration went through. However, I faced a new (simpler) issue because I can’t access Home Assistant from homeassistant.local:8123. So I needed replace my Home Assistant URL with the correct one ( homeassistant:8123).

And now it finally works!

3

Ive managed to get things fully setup…and its working 95% of the way…I change temp in HA, app and phyical thermstat show the relevant changes…

But if I set the temp in the app, or on the thermostat itself or via Alexa…the Home Assistant temp set DOES NOT change…all of these three set each other…but do not show a change in Home Assistant…well not unless I reload the integration, which cant be the only way to get an update

Is this by design…is it meant to ONLY work like a 1 way street?