I am getting errors like the following screenshots when I try to append this to the URL. Any ideas?

@timur-g

Collabora error fixed with CollaboraOnline/online#10198.

I've done some research into how we could implement this in richdocuments. So far, this is my analysis and proposed solution:

First, I tried to solve the problem of the &startPresentation=true parameter being removed from the URL when you try to open a presentation from within Nextcloud. This ended up being due to the file action which the viewer app registers; it uses OCP.Files.Router.goToRoute() to navigate to a very specific route, providing its own queries / parameters (thus erasing all others you give it manually). I cannot find a workaround for getting the parameter in richdocuments unless I use some hacky solution or something changes with how the viewer handles this, but with such a small addition I doubt it would be worth it to change anything there.

With that being said, my proposed solution would be to register a file action on presentation files which would immediately open them in presentation mode. It's one more click to show the file action menu, and you couldn't, for example, simply share a link to a presentation which would open it automatically in presentation mode, but it would provide a cleaner solution in my opinion.

Any thoughts or ideas which I haven't thought of?
@juliusknorr and @timur-g (in case you want to stay up-to-date)

A quick option would be to check for the parameter on page load in PHP and pass it to the richdocuments frontend code as initial state or store it in the session if it needs to persist multiple page reloads due to redirects.

Cleaner option would be if the files app could preserve url parameters somehow, but might be larger effort