I am stuck here.
I did upgrade owncloud to version 10.3.0.4 from a 9.x Version in two steps. First to 10.0 then 10.3.
The gallery app is up to date (16.1.1).
But when I open the gallery app it is not showing anything. All blank. I have no warnings or errors in the log file.
I re-installed the gallery app. But this did not change anything.
If you still really really want to use it you could download an old version from github, put it in your apps directory and enable it, however I absolutely see no reason to do so
As a side note I would recommend to move to 10.3.1 straight away.
I was so busy fixing that issue, that I did not realize that the gallery app is deprecated!
I will try the media viewer later today.
Do you know if the media viewer als has some kind of gallery?
As soon as I removed the Media Viewer the Gallery app was working again.
The Media Viewer is no replacement nor improvement (as advertised) - so for now I will stick with the gallery. Even if it is no longer maintained.
Thank you for you comments!