Question: Preview app no longer works in High Sierra
Preview seemed to work fine at first. I don't know if it's related, but I noticed Preview refused to open anymore after the latest Firefox Quantum browser update.
For some reason, High Sierra suddenly set "Grab" as the default image viewer, and that's an aggravating substitute.
Both my old (late 2009) and new (2017) Mac had problems with Preview (and TextEdit) after the last Sierra update. Then it refused to open most files located anywhere other than the built-in hard drive. Now Preview won't open at all on the old Mac no matter where the file is. (Works fine so far on the new one).
I've tried Preview Reset and the other fixes suggested in these forums to no avail.
I would try trashing the prefs but they don't exist: there is nothing here: ~/Library/Containers/com.apple.Preview