Nest + Home Assistant: Check Your Pub/Sub Topic Before November 30

If you connected Nest cameras, doorbells or thermostats to Home Assistant a while ago, there's a deadline coming that won't throw an error. Things will just get quiet.

Google's Device Access release notes from September 29 put it plainly: "Event notifications will no longer be published to Google-hosted Pub/Sub topics after November 30, 2026." After that, apps on those topics "will no longer receive real-time device state updates or trait events."

In Home Assistant terms, that's the stuff your automations actually run on. Doorbell chime events. Motion and person events from cameras. The Nest integration docs say thermostat state changes and sensor updates also come in through the Pub/Sub subscriber, so I'd expect those to go stale too.

Who's affected

Not everyone. Google stopped offering Google-hosted topics for new projects on January 23, 2025. If you set up your Device Access project after that, you created your own topic and you're probably fine.

The ones to check are setups from before that date where the Device Access Console created the topic for you. If you don't remember which you did, that's fine. The check below takes two minutes.

The two-minute check

Open the Device Access Console, pick your Home Assistant project, and look at the Pub/Sub topic.

• If it starts with projects/sdm-prod/topics/, it's a Google-hosted topic. You need to move.
• If it starts with projects/<your-cloud-project-id>/topics/, it's yours. No action needed.

That's the same test Home Assistant's own docs now use. The developers' code checks for that projects/sdm- prefix too.

The fix, today

You can do this now with the current docs. In short:

1. In the Google Cloud console, go to Pub/Sub and create a topic in your own project. The docs use home-assistant-nest as an example ID.
2. Open that topic's Permissions tab, add sdm-publisher@googlegroups.com, and give it the Pub/Sub Publisher role. Do it on the topic itself, not on the project's IAM page. The docs call that out specifically.
3. Back in the Device Access Console, disable the old topic and enable events with the full name of your new one.
4. Point Home Assistant at the new topic.

Step 4 is where it gets annoying on the current release. Until now, changing the topic meant removing the Nest integration and setting it up again, which is exactly the chore that makes people put this off.

What Home Assistant is adding

Allen Porter, who maintains the Nest integration, got two changes merged in late October that make step 4 a lot less painful.

The first (PR #187156) adds a Reconfigure option to the Nest integration. It lets you "select or create a different Pub/Sub topic in their Google cloud project, without removing and re-adding the integration." It reuses your existing sign-in if it's still valid and only asks you to log in again if Google revoked it. The topic and subscription pickers default to what you have now.

The second (PR #188119) adds repair warnings. If your entry is on a Google-hosted topic, you'll see a legacy_pubsub_topic warning telling you to run Reconfigure. There's also a new error repair for a missing Pub/Sub subscription. That's worth having on its own, because the Nest docs note that Google deletes Pub/Sub subscriptions after 31 days of inactivity by default.

When I checked in late October, both were merged into Home Assistant's development branch but not in a stable release, so 2026.11 is the likely vehicle. That's my inference, not an announcement. Check the release notes for "Nest" and "Reconfigure" before you count on it.

Costs and side effects

Two things people worry about, both answered in Google's note:

• Your sign-in survives. "Migrating your Pub/Sub topic configuration does not invalidate existing user access tokens or OAuth permissions."
• It might cost something, but probably not. A topic in your own project falls under standard Google Cloud Pub/Sub pricing, which includes a free tier of 10 GB per month. A household's worth of Nest events shouldn't come close to that, but it's your Cloud project now, so it's your bill to watch.

What I'd do

Check now. It takes two minutes to find out whether you're affected, and the deadline lands at the end of a holiday month when nobody wants to be fixing the doorbell.

If you're on a legacy topic and comfortable in the Google Cloud console, do the manual migration now and don't wait for the Reconfigure button. If you'd rather not remove and re-add the integration, update Home Assistant when the release with Reconfigure lands, then follow the repair notice. Just don't leave it for the last weekend of November.

Afterwards, test it. Press the doorbell or walk past a camera and watch the event entity update in Home Assistant. If nothing happens, the docs' troubleshooting section walks through checking published message counts on the topic and subscription, and turning on debug logs to look for "Received 1 messages" lines from the Nest library.

This is the price of cloud control. Nothing on your network changed, and your automations can still stop working on a date somebody else picked. At least this time there's a date, a fix, and a few weeks of warning.