System crashes immediately after boot, any troubleshooting tips?

[brystmar (Thomas)]

Might be the wrong forum? Apologies if so.

Running HA 2025.8.3 bare metal on a dedicated NUC. It’s been stable and reliable until mid-morning today when my wife noticed her media on a smart speaker kept getting reset. I pulled up the HA companion app on my phone and found it couldn’t connect; the system would restart itself sporadically. I have HA log some events like startups & shutdowns to a private Discord server. Shutdowns aren’t getting listed because the system is crashing:

Fortunately, HAOS is stable when booted to safe mode. Nothing looks particularly fishy, but there’s no harm in restoring from last night’s backup. This is why I store 35 days of full backups, right?

Restoring the 8/30 @3am backup yields the same behavior above. System is immediately unstable once HA finishes loading everything. Same with the 8/29 backup. And the 8/28, the 8/25, and even the 8/15 from when we were out of town. This behavior never materialized before today.

Maybe it’s a hardware issue. How about we spin up a VM and try restoring each of those backups to the VM? Same issue. This time, I could see the VM running out of memory as it crashed – even after bumping it up to 12GB RAM. Something’s up.

The VM did show this CIFS error while booting, though I’m skeptical that a faulty connection to the NAS would be the culprit.

The only hardware or device change I made this month was plugging in the new ZWA-2 when it arrived on 8/26. I haven’t had a chance to set it up yet, or even have HA recognize it yet – just plugged in the USB. My backup restores were all conducted with it unplugged, so it’s unlikely the culprit.

I’m stumped here. I tried disabling integrations like HACS and other third-party additions with no success. My next step tomorrow is to disable every non-first-party integration, reboot, add a couple back in, then continue the cycle in hopes of finding something that will boot properly again. Each full reboot + restart in safe mode takes ~10 minutes, so that’ll be fun. Any troubleshooting ideas beyond that?

[tom_l]

@brystmar

Fortunately, HAOS is stable when booted to safe mode.

This means it is a third party integration or dashboard resource. They are not loaded in safe mode.

Start in safe mode again and look at your config/home-assistant.log.1 file. This is the log from before the last restart.

[Sir_Goodenough ((SG) WhatAreWeFixing.Today)]

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[brystmar (Thomas)]

The .log.1 file helped me narrow my search, thank you. The culprit was either:

• An automation that regularly queried a sensor for a threshold. That sensor’s output was recently changed without me realizing it.
• The UniFi Network integration. I subscribe to the regular, stable release channel, and this is a fairly popular integration, so there’s a decent chance this is a false-positive.

Both were disabled in my last reboot, and I don’t dare tempt the gods any further on a long weekend. This ordeal reignited my interest in the High Availability Home Assistant guide.

[fleskefjes]

High Availability would not help in this case. If it was an automation causing the crash, that automation would have been replicated to the other instance.