good point, and correlation with 1.5.X update of course doesn't mean causation, no question.
The webcamd logs for the moment of fail are the following lines (before that, and after a manual SSH triggered webcamd restart its working nicely):
Dec 11 08:07:05 octopi webcamd: i: select() timeout
Dec 11 08:07:05 octopi webcamd: i: cleaning up resources allocated by input thread
Dec 11 08:07:05 octopi mjpg_streamer: MJPG-streamer : select() timeout
Dec 11 08:07:05 octopi mjpg_streamer: MJPG-streamer : cleaning up resources allocated by input thread
I am pretty sure it's not a simple system power issue because my raspi 4b is getting its power from a 65w USBC powerbrick meant for much thirstier machines (plus this exact identical setup was working nicely for about half a year while 1.4.X and lower versions were running on the pi).
From Octoprint's log, the only anomaly is:
2020-12-11 08:12:18,236 - octoprint.timelapse - ERROR - Could not capture image /home/pi/.octoprint/timelapse/tmp/[printing filename]
Traceback (most recent call last):
File "/home/pi/oprint/local/lib/python2.7/site-packages/octoprint/timelapse.py", line 750, in _perform_capture
File "/home/pi/oprint/local/lib/python2.7/site-packages/requests/api.py", line 76, in get
return request('get', url, params=params, **kwargs)
File "/home/pi/oprint/local/lib/python2.7/site-packages/requests/api.py", line 61, in request
return session.request(method=method, url=url, **kwargs)
File "/home/pi/oprint/local/lib/python2.7/site-packages/requests/sessions.py", line 530, in request
resp = self.send(prep, **send_kwargs)
File "/home/pi/oprint/local/lib/python2.7/site-packages/requests/sessions.py", line 643, in send
r = adapter.send(request, **kwargs)
File "/home/pi/oprint/local/lib/python2.7/site-packages/requests/adapters.py", line 529, in send
raise ReadTimeout(e, request=request)
ReadTimeout: HTTPConnectionPool(host='127.0.0.1', port=8080): Read timed out. (read timeout=5)
2020-12-11 08:17:25,716 - octoprint.server.heartbeat - INFO - Server heartbeat <3
Not sure which more verbose log could help here.
Of course, could also hypothetically be a busted ribbon cable or a hardware glitch of some kind (I naturally don't have spares of every component at hand to investigate) - but then I think it's at least suprising how running sudo service webcamd restart gets everything fixed temporarily every time.