I tried to integrate Nest into HA a year or two and after hours of frustration I eventually gave up. I tried again this morning and have had no better luck.
Following all the steps described here
Once done I am back in HA attempting to integrate. Once I enter my Device access ID I click “Submit” and a new web page opens. The first time the only thing on this page was “Opps, something went wrong”. I review my work and tried again. This time, after the submit, I get “Can’t link to Ha-Nest
Please contact Ha-Nest if the issue persists”
It may be that there’s authentication data lying around from last time. If it shows up in “Settings > Devices and Services > 3-dots > Application Credentials”, delete and retry.
Got a pleasant surprise this afternoon. I noticed that Google Nest was now on my Integration screen with the Configure button. Repeated the same steps as above and voila… It worked.
God Michael, you helped me ton! This BS with google, and incredible complex setup for smart devices was driving me nuts. OAuth was my issue, I creaded two used old and went through the cycles until I saw your suggestion.
Thanks much …