Any update on this? I don’t think the “last_updated” field should be updated when HA restarts. We only want the field to be updated when the device or entity sends a physical update, correct?
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I have an approach how we can do this,
Making a area just like they did with Nabu Casa Alexa and Google.
Where all supported devices populate, and u can SELECT whats supported to retain the data.
Because i know there is a reason why they did not implement this by default, but making us selecting the entities from a list to include the last-changed or last-updated attribute would solve it.
So no reason to not do it, i did upvote it !
with devices i mean entities, sorry was for to long at homeseer.
Unfortunately, despite the great response in votes, the request has not yet been implemented. If it is helpful, I have shared some examples of sensors to keep the last_state on reboot.
Bumping this, really annoying
Nice to quickly see when a device was last used, motion detected
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Yep. Not so nice to have 100 sensors that tells you when you restarted Home Assistant as per current behaviour. More useful to preserve the actual last change/update rather than last restart of HA core 
But for some reason, people developing the HA core does not like this so it probably will not happen. You will have to write custom automations/triggers and update the state of your additional helpers to fix this. Bloating everything.
It has been discussed before, and for a long time, e.g. here:
A lot of bumps. No code change 
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I hope you found the answer since then, but just in case: last_changed records the last time the value was changed, last_updated the last time the value was given.
If the sensor receives a new value and it is the same as the old value, it will only affect last_updated, not last_changed.
Nah! I’m still running 0.94 and haven’t rebooted in years…
Yes, I have, thanks!
At the risk of being accused of throwing the baby with the dirty water, I wonder if it would be worth just removing these. Almost anything you base off of these will
- at best create many questions from household members and yourself of why the data seems wrong
- at worst, produce really wrong behavior that causes false alarms and notifications and family scares
For as long as we need to restart HA regularly – minimally once every few weeks to pick up latest updates, and for some of us, much more frequently, these fields are either useless or confusing or dangerous.
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Big plus one. The only reason why I realized I needed this was the awesome multiple entity row card: GitHub - benct/lovelace-multiple-entity-row: Show multiple entity states and attributes on entity rows in Home Assistant's Lovelace UI
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Thereis one more downside of this, and that is current implementation of “device triggers”. If you don’t use state trigger “door sensor state goes from off to on”, but use “device trigger” su as “door opened”, it doesn’t hav the “from” condition. And that means, after restart, change from “unknown” to “on” happens, which triggers any automation that has “when door opens”. That’s clearly wrong, as the doors didn’t move an inch.
Zigbee lights supports one nice functionality: power on behaviour. And you can choosefor yourself whether you want the light to stay off or go to it’s previous state when power is lost and then restored.
Nabu Casa people think it’s absolutely necesary to change status of every single thing, and trigger all automations after restart, while users think the oposite (as seen in the votes and discussion in similar topics). Why not implement HA variant of “power on behaviour”? Just a simple boolean in settings. Do you want every single change sensor to trigger change and update last-changed after restart? Your choice. That would make Nabu Casa people have it their way, while allowing users to set it to their preference. Could that be implemented?
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Bumping this.
I have been trying to implement a watchdog for my MQTT devices to check when they were last seen, the current solution I have is disrupted on every restart. My logic is if an MQTT device last changed > 24 hours ago, then flag as potentially disconnected. If I restart HA (once a week for updates or multiple time a day if I’m working on something), I lose the last time the device checked in so my watch dog is useless for 24 hours after a restart.
Bumping this as well. I need to keep a closer look at by battery devices.
Just last week a Smoke detector (Fibaro) kept stuck on 40% battery left. DIgging in to it stopped logging changes battery/temperature etc for weeks already.