Pi-hole is running on a Raspberry Pi B+ with the latest version of Raspberry Pi OS. There were no unusual events during installation or while it was running. I was able to monitor the activity on my iMac with Safari, using the latest versions of the software. The Pi-hole sits on a simple home LAN with all direct cabling, not WiFi.
Actual Behaviour:
However, 3 times the unit stopped working and would no longer boot. I did a complete reinstallation of Raspberry Pi OS and the Pi-hole software. It worked for a while, then repeated the annoying crash.
Good point. I was missing the forest for the trees. I'll reload Raspberry Pi OS only and let the Pi just run.
The B+ is no longer bootable since the software is corrupted. Therefore I suspected there is no debug information. I'll pull the SD card and try to read it on another system.
Update: The bare bones Pi is running without any issues. Now it's time to load and activate Pi-hole. I see no reason why it should work this time around, but it's easy enough to set up.
As the Pi didn't boot, the filesystem was corrupted. That often indicates a dying SD card. So having a raw Raspberry Pi OS without installing and running any software on it (inducing filesystem writes) is not a valid test to narrow down the issue to Pi-hole.
However, usually I/O errors start before the system crashes. So regularly check for related kernel errors after you installed Pi-hole:
dmesg -l emerg,alert,crit,err
Also did checking the /var/log files from the broken image from an external system show something?
Good information, thanks! If there's any chance of a bad SD card, I'll replace the one I have and then put the system in play. I didn't check the log files, but I'lll try if this happens again.