Hello,
The weather has been bad for the past few weeks so I was just playing with my setup installing all the new updates.
Everything was working fine until today... It's not related to the recent updates since I did restore a month old backup and it shows the same behavior (and was working fine before).
I have two cameras attached - ZWO CCD and Nikon DSLR. No problem with ZWO.
Оnce I hit "preview" for Nikon, RPI reboots immediately! (and Nikon says "ERROR press shutter release button again")
What can be wrong?. The INDI settings are unchanged/good. Hardware is the same (worked a few days ago) .
Loose cables? Checked those.
What else can be wrong?
Thanks!

sorry. was some strange power (not enough of it) problem.
EDIT: really strange. Works with a Nikon battery. Crashes with a dummy battery adapter (5V USB to 8.4V Nikon) - used to work just fine. : (

[EDITED]
Figured it out...
12V power supply was the culprit. It powers a USB hub which in turn powers the RPI (5V) and the Nikon (via 5V-to-8.4V adapter).
I have five 12V supplies on my power strip (three battery chargers, monitor and another one for the hub) - by mistake I used one of the battery chargers which outputs 12.6V instead of 12. The Nikon didn't like it.
Switched to the right supply - all is well.

Noooo.... It's actually new kstars/ekos! or something else? (using today's nightly 3-6-19)
Boot up without even starting kstars - switch on the camera - crash (RPI just restarts)!
Boot with the camera switched on - switch off the camera - crash!

Restored a backup (3.0.0 build from Nov. 5 2018) - no such symptoms.. same story!
And I am sure a week ago everything was fine.

I keep talking to myself...
Definitely some sort of a power issue...
The camera was powered from one of the "red" USB sockets of the hub (no data, only DC - 5.1V actually).
Hooked it to a regular USB port - boom... now it works as it should.
Strange. Maybe the 5V-to-8.4V adapter is misbehaving..