This has happened again. Identical symptoms. www was no longer a member of shared group. I noticed that the group file was last touched on the same date I last applied updates.
Confirmed that this gets removed when applying updates:
- Re-inserted the www into shared group (usermod -a -G shared www), rebooted
- Verified that root web page is now accessible
- Applied latest updates via UI
- Noted www was still present in shared group
- Issued signal-event post-upgrade; signal-event reboot via shell (UI had closed, was inaccessible)
- When dust had settled, it was broken again.
Presumably my cert should update now ...