Something broke in your Home Assistant setup and you need it fixed. Here are the 15 most common problems and how to actually solve them.

1. Zigbee Device Keeps Going Offline

Symptom: A sensor or switch shows “unavailable” periodically, then comes back.

Fix: This is almost always a mesh problem. The device is too far from a router.

• Add a mains-powered Zigbee device (smart plug, bulb, or repeater) between the coordinator and the problem device
• Check your mesh map in Zigbee2MQTT — look for red/weak connections
• Move the coordinator’s USB dongle to a USB extension cable (3+ feet) away from the HA server. USB 3.0 ports generate 2.4GHz interference that kills Zigbee

2. Automation Not Triggering

Symptom: You set up an automation and it never fires.

Fix: Check these in order:

1. Is the automation enabled? Settings → Automations → check the toggle
2. Is the entity ID correct? Go to Developer Tools → States and verify the entity exists and has the state you’re triggering on
3. Check the trace: Settings → Automations → click your automation → Traces. If there’s no trace, the trigger never fired. If there’s a trace with a failed condition, your conditions are blocking it
4. Mode conflict: If the automation is set to mode: single and it’s already running (from a previous trigger that hasn’t finished), new triggers are silently dropped. Try mode: restart

3. “Entity Not Found” Errors

Symptom: Dashboards show “entity not available” or automations reference entities that don’t exist.

Fix: Entity IDs change when you rename devices or reinstall integrations.

• Go to Developer Tools → States and search for the entity
• If the entity was renamed, update your automations/dashboards with the new ID
• If the entity is truly gone, re-add the device or integration

4. Home Assistant Is Slow

Symptom: The UI takes seconds to load, automations have noticeable delay.

Fix: Common causes:

• Database bloat: Settings → System → Recorder. Exclude entities you don’t need history for (like binary sensors that change every second). Add to configuration.yaml:

recorder:
  purge_keep_days: 5
  exclude:
    entity_globs:
      - sensor.sun_*
      - binary_sensor.*_motion

• SD card: If running on a Raspberry Pi with an SD card, the card is probably dying. Switch to USB SSD boot — it’s night and day.
• Too many integrations polling: Check Settings → System → Logs for integrations that are erroring repeatedly. Each failed request adds latency.
• Low memory: Check System → Hardware. If RAM is consistently above 80%, you need more or need to reduce integrations.

5. Can’t Access HA Remotely

Symptom: HA works fine on local network but you can’t reach it from outside.

Fix: You need one of:

• Nabu Casa ($7.50/mo) — easiest, supports remote access and voice assistants
• Cloudflare Tunnel — free, runs a tunnel from your server to Cloudflare
• VPN (WireGuard/Tailscale) — connect to your home network remotely, then access HA normally
• Reverse proxy (Nginx, HAProxy) — for advanced users, requires port forwarding

Don’t expose port 8123 directly to the internet. Always use a tunnel, VPN, or reverse proxy with HTTPS.

6. Zigbee Device Won’t Pair

Symptom: You put the device in pairing mode but it never shows up.

Fix:

1. Make sure permit join is actually enabled (check Z2M dashboard or ZHA)
2. Move the device within 3 feet of the coordinator for initial pairing
3. Factory reset the device (hold the button for 10+ seconds on most Aqara/SONOFF devices)
4. Try pairing while the device is already powered on (some devices only enter pairing mode during power-on)
5. Check if your coordinator firmware supports the device — update coordinator firmware if needed

7. Companion App Not Sending Location

Symptom: Person entity shows “unknown” or never updates.

Fix:

• iOS: Settings → HA Companion → Location → make sure “Always” is selected for location access. Also enable “Background App Refresh”
• Android: Battery optimization must be disabled for the HA app. Settings → Apps → HA → Battery → Don’t optimize
• Check that your phone’s location services are actually on
• The app needs to be opened at least once after a phone restart

8. MQTT Not Connecting

Symptom: Zigbee2MQTT or other MQTT integrations show “disconnected.”

Fix:

• Restart the Mosquitto broker add-on
• Check that the MQTT user exists: Settings → People → Users (Mosquitto creates its own user)
• Verify the MQTT port isn’t blocked: default is 1883
• Check Mosquitto logs for authentication errors
• If you changed the Mosquitto password, update it in Z2M’s configuration too

9. Sensors Showing Wrong Values

Symptom: Temperature reads 150°F, power shows negative watts, etc.

Fix:

• Temperature: Check if the sensor is in °C but you expect °F (or vice versa). HA converts automatically based on your unit system setting
• Energy monitoring: Some devices report in W, some in kW. Check the unit
• Stale data: If a sensor shows an old value, check its last_updated in Developer Tools → States. If it hasn’t updated recently, the device may be offline
• ADC sensors (ESPHome): Calibration is probably off. Re-read raw values and adjust your thresholds

10. Automations Fire at Wrong Time

Symptom: Time-based automations trigger at the wrong hour.

Fix: Your timezone is probably wrong.

• Settings → System → General → Time Zone
• Also check your system clock: Developer Tools → Template → type {{ now() }} and verify it’s correct
• If running in a VM, make sure the VM host’s clock is synced

11. Update Broke Something

Symptom: Everything worked before the update, now it doesn’t.

Fix:

1. Read the release notes — HA breaking changes are documented at every release
2. Check the logs: Settings → System → Logs. Look for errors with entity names or integration names
3. Restore from backup: Settings → System → Backups. This is why you keep backups.
4. Don’t update on day one — wait 3-5 days for hotfixes. The HA community finds bugs fast

12. Dashboard Card Shows “Loading”

Symptom: A card on your dashboard is stuck on “Loading” or shows an error.

Fix:

• Clear browser cache: Hard refresh (Ctrl+Shift+R)
• Custom card not installed: If you’re using HACS cards, make sure the resource is loaded. Check Settings → Dashboards → Resources
• Entity doesn’t exist: The card references an entity that was removed or renamed

13. Can’t Install Add-on

Symptom: Add-on installation fails or the add-on won’t start.

Fix:

• Disk space: Check System → Hardware. Add-ons need room to download and install
• Architecture mismatch: Some add-ons don’t support all hardware (ARM vs x86)
• Network issue: The HA server needs internet access to download add-ons
• Try: Settings → System → Restart, then install again

14. Device Shows “Unavailable” After Reboot

Symptom: After restarting HA, some devices show unavailable for minutes.

Fix: This is usually normal. Different integrations take different amounts of time to reconnect after a restart.

• Zigbee devices: 30-60 seconds
• Wi-Fi devices: 1-2 minutes
• Cloud integrations: 1-3 minutes

If a device stays unavailable for more than 5 minutes, that’s a real problem — check the integration logs.

15. Can’t Edit YAML Files

Symptom: You want to edit configuration.yaml but can’t find it or access it.

Fix: Install a file editor:

• File Editor add-on: Settings → Add-ons → Add-on Store → File Editor
• VS Code add-on: Same path, search for “Studio Code Server” — more powerful
• SSH: Install the Terminal & SSH add-on for command-line access
• Samba: Install the Samba add-on to access config files from your PC’s file explorer

Prevention

Most problems are avoidable:

• Keep backups: Automated daily backups. Test restoring one occasionally.
• Don’t update immediately: Wait a few days after a new HA release
• Build a proper Zigbee mesh: 1 router per 5-6 battery devices minimum
• Use an SSD, not an SD card: If running on a Pi
• Monitor your system: Set up alerts for disk space, memory, and device availability

For a solid foundation, check my beginner’s guide and my best Zigbee devices guide for reliable hardware that causes fewer headaches.