Home Assistant with Nabu Casa is the closest thing to a hybrid smart home: mostly local, cloud only for the parts that need to reach the outside world. When Nabu Casa has an outage, the confusion for owners is not what stops working, but figuring out which of their working-a-minute-ago things depend on it and which do not. This guide covers exactly what Nabu Casa handles, what keeps running when it is down, and how to test your setup for cloud dependency without waiting for the next outage.
What Nabu Casa actually does
Nabu Casa is Home Assistant’s cloud add-on service. For a monthly fee, it provides four specific services, each with its own failure mode:
- Remote UI. A secure reverse tunnel that gives you https access to your Home Assistant instance from outside your home network without opening a port on your router.
- Google Assistant integration. Bridges your Home Assistant entities to Google Home so you can say “Hey Google, turn off the kitchen light” and reach a Home Assistant switch.
- Alexa integration. Same as above for Alexa.
- Text-to-speech and speech-to-text. Cloud voice services that Home Assistant’s Assist feature uses when a local model is not installed.
Everything else runs locally: your Zigbee mesh, your automations, your Lovelace UI on the local network, your MQTT broker, your integration to Hue Bridge or Aqara Hub, and any Matter devices commissioned directly. A Nabu Casa outage does not affect these.
What breaks when Nabu Casa is down
| Function | Behavior during outage | Workaround |
|---|---|---|
| Home Assistant UI on your local network | Works | None needed |
| Home Assistant UI from outside your home (Remote UI) | Fails to load | VPN back to your network, or wait |
| Google Assistant “turn off kitchen light” targeting a Home Assistant entity | Google responds “Sorry, I could not reach the device” | Use physical switch or Google Home native devices |
| Alexa routine that calls a Home Assistant switch | Routine skips that step silently | None |
| Any Home Assistant automation not using Assist/TTS | Works | None needed |
| Assist voice pipeline using Nabu Casa STT/TTS | Fails, voice input times out | Install local Whisper + Piper add-ons before outage |
| Home Assistant app on your phone (from home Wi-Fi) | Works | None needed |
| Home Assistant app on your phone (from cellular) | Fails to load (Remote UI down) | Enable VPN if configured |
How to know which of your automations depend on cloud
The safest test is to disable your internet connection at the router level for 15 minutes on a low-stakes evening and observe what stops working. That is heavy-handed and inconvenient. A less disruptive way:
- In Home Assistant, go to Developer Tools, Services. Trigger each automation manually by calling
automation.trigger. - Watch each action node in the trace. Any action that calls a cloud-only service (like
tts.cloud_say,google_translate_say, or an integration marked as “cloud polling”) will be your first suspect when the cloud is unreachable. - Anything that uses the Alexa Media Player integration or a REST call to an external API will also fail during a cloud outage.
Under Settings, Devices and Services, each integration has a small cloud icon if it uses cloud polling. Count how many of your entities come from cloud-dependent integrations. In practice, most setups have 15% to 30% of entities on cloud-dependent integrations even when the user thought they were “all local.”
Reducing your cloud footprint before the next outage
Three real changes give you the biggest resilience gain:
- Move Google Assistant / Alexa off Nabu Casa for critical devices. Devices that your household must be able to voice-control should ideally be native Google or Alexa devices (not Home Assistant-bridged). A Nest thermostat controlled by Google is more resilient than a Zigbee thermostat bridged through Nabu Casa.
- Install the Whisper and Piper add-ons for local voice. These give you offline speech-to-text and text-to-speech that work during any cloud outage. Whisper needs about 2 GB of RAM; Piper is lightweight.
- Set up a local Wireguard or Tailscale VPN for remote access. This is a Nabu Casa Remote UI alternative. When Nabu Casa is down, your VPN still gets you into your local network.
The two-hour outage in July 2026
Nabu Casa had a two-hour partial outage on July 8, 2026, affecting the Google Assistant bridge specifically. Home Assistant instances themselves were fine; only the Google-to-HA bridge was unresponsive. Community reports showed:
- Voice commands to Google to control Home Assistant entities: fail rate near 100%.
- Home Assistant automations that ran on time-based triggers: 100% success.
- Home Assistant automations that used a Google Assistant integration event as a trigger: 0% success.
- The Home Assistant mobile app inside the home network: fine.
- The Home Assistant mobile app from cellular: unreliable because the app uses Nabu Casa Remote UI for external access.
Frequently asked questions
Does my Home Assistant history keep getting recorded during a Nabu Casa outage? Yes. The Recorder integration writes to the local SQLite or MariaDB database and does not depend on Nabu Casa.
Can I check Nabu Casa status without leaving Home Assistant? The Nabu Casa integration exposes a sensor called binary_sensor.cloud_online that turns off during outages. Add it to a dashboard for at-a-glance status.
If Nabu Casa is down, will my Matter devices still work? Yes. Matter devices commissioned to Home Assistant use the local Matter Server; they do not touch Nabu Casa.
Does the outage cost me my Nabu Casa subscription time? Nabu Casa credits users’ accounts for outages exceeding their published SLA. Their support policy is documented at nabucasa.com/support.
Is there a way to make Google Assistant fall back to local if the cloud bridge is down? Only for Google-native devices. Home Assistant entities bridged through Nabu Casa cannot be reached without the Nabu Casa bridge.
Does Home Assistant Cloud include remote push notifications? Yes. Push notifications to the Home Assistant Companion app use Nabu Casa’s push server. During an outage, notifications queue on the app’s device but do not deliver until the cloud recovers.
Can I self-host a replacement for the entire Nabu Casa stack? Yes. Cloudflare Tunnel for remote UI, self-hosted Whisper and Piper for voice, and Home Assistant’s native Google Assistant and Alexa integrations (which require running your own HTTPS endpoint with a real certificate). It is significantly more setup than Nabu Casa and worth it only if you want zero cloud dependencies.
Is my two-factor authentication code delivery affected by a Nabu Casa outage? No. Home Assistant 2FA (TOTP) is entirely local and does not touch Nabu Casa. It generates and validates codes locally on the server.
