When I execute this via CLI:
"C:\Program Files\GPSoftware\Directory Opus\dopusrt.exe" /prefs
Opus immediately crashes with this error message:
I'd taken the "%1" off of the end of that command, which I'd found while looking for something else in the registry, and since that means that the command would have received a file or path from Opus, I assume that's why it crashes in DOS. I also assume that since I've not been seeing this crash in normal operation, it's probably my fault it's appearing.
We've fixed that for the next update.
AFAIK DOpusRT /Prefs ... is undocumented and for internal use, so you shouldn't depend on it. We may remove or change it as needed in the future. (It still shouldn't crash, of course.)
If you just want to open Preferences from outside of Opus, use this:
DOpusRT.exe /cmd Prefs
That uses documented and supported commands / arguments which should always work in the future.
I should probably say that I wasn't trying to do anything with it, I was looking for something DOpus related in the registry and thought that might have been related. I dropped the %1 because I know that's DOpus syntax and therefore assumed it wouldn't work in DOS. Anyway, good to know it's already history.