Home Assistant Automation Running by Itself? Check the Empty "From" Box

An automation in my house ran by itself. It cleared the switch that tells my house "someone's in here, leave the lights on", and it's only supposed to do that when the room goes dark. The light never went off. What happened: for a fraction of a second, Home Assistant lost track of a sensor. Unavailable. On the way back, the sensor passed through "off", and the automation took that as the room going dark. The trigger had "To" filled in and "From" left empty. Empty doesn't mean "from open" or "from on". It means from anything, and unavailable counts as anything. In plain English (the full version is in the pinned comment): Unavailable: Home Assistant's word for "I can't reach this device right now." State trigger: the classic way to start an automation when something changes. From / To: the two boxes on a State trigger. "From" is optional, and that's the trap. Three fixes: 1. Fill in "From". Door: from open to closed. Sensor: from on to off. 2. "Not from: unavailable, unknown". Every real change still counts; only the comeback is ignored. It's a few lines of YAML, because the visual editor can't show it. 3. The newer triggers (Add trigger → By type → "Door closed", "Light turned off"). They ignore the comeback on their own. They don't cover everything: my template sensor only gets the old State trigger. How to find yours: Settings → Automations → Filters → Entities. Pick a device that drops out now and then. Open each automation it lists and look for a trigger with "To" filled in and "From" empty. (The search box won't find these; it doesn't look inside triggers.) Starter prompt to have an AI check your automations for this: https://gist.github.com/pcamp99/e3529... 0:00 It ran by itself 0:19 What the automation saw 0:45 The fix, shown working 1:16 Why an empty "From" box fires 1:49 What it cost in my house 2:22 Fix one: fill in "From" 2:44 Fix two: "Not from" 3:06 Fix three: the newer triggers 3:25 Where fix three doesn't reach 3:39 Find yours 4:15 Check your "From" Filmed on Home Assistant 2026.9. I'm not a coder. I use Claude for basically everything technical in my home automation setup. This channel documents the gaps nobody tells you about. #homeassistant #smarthome #homeautomation