After upgrading from 9.1.4 to 1.9.5, the installed bookmarks app is no longer available.
The app directory mentions:
Bookmarks 0.9.0 by owncloud (AGPL-licensed) (Approved), which cannot be enabled.
Client error response [url] https://apps.owncloud.com/CONTENT/content-files/174834-jj%3Cimg%20src= [status code] 404 [reason phrase] Not Found
Any idea, what could be wrong?
Seems someone broke / hijacked the app download at https://apps.owncloud.com/content/show.php/Bookmarks?content=168710
cc @Kawohl @DeepDiver1975 as you guys seems to be active at https://github.com/owncloudarchive/bookmarks/commits/master
We observed this on some other apps as well ... strange 
...
Some one found a vulnerability in the appstore and is now injecting broken stuff? Former ownCloud member / app developer with access to that app breaking the links intentional? Something else changed at apps.owncloud.com?
I'm afraid, yes. As a consequence, I'll stop using that app store, it's beyond any trust. A possible next step could be, stopping the use of oc at all.
Probably one of the many reasons why https://marketplace.owncloud.com/ was created 
It was really time to get rid of that old thing and its great that the ownCloud company put the effort into building up such a new infrastructure from scratch to have a sane infrastructure for publishing apps
I see. But why is oc 9.1.5 still addressing that crappy old store?
You just can switch out one appstore with another one. AFAIK this was a rewrite of the app handling / updating / installation mechanism in oC to have a more sane base.
Could you by any chance tell me/us how to do this? I made several Google searches but couldn't find any result that seemd to work.
Telling you what to do?
I would like to use https://marketplace.owncloud.com/ or some other place as the default source from which my owncloud gets it's apps. The default place does not seem trustworthy anymore, as alfredb said.
Or am I better off installing the apps manually?
I would agree here, but I'll wait until the new marketplace is fully populated and out of beta state.
Only ownCloud 10.0.0 and up is using the marketplace as a default. If you would use "some other place" in oC 9.1.x or below you would need to setup an own appstore.
Currently only owncloud 10 can interact with marketplace.owncloud.com
But as we speak I'm developing an API in the new marketplace which allows owncloud 9 and owncloud 9.1 to get apps from the marketplace. We will soon announce on how this can be used.
It also takes some time until all developers move their apps to the marketplace.
But yes - the bloody old appstore has to die!
couldn't agree more.
So - if you miss an app on marketplace.owncloud.com please contacts the app developer and ask him to publish the apps there. For any issues you are facing please open an issue at https://github.com/owncloud/marketplace-issues/issues
Thank you for working on this and answering the question.
Is there an answer to the original question? This is preventing me from using certain apps at the moment.
Well, my solution was, getting the app from github and installing it manually.
I downloaded the zip file, changed the name of the directory to "bookmarks", moved it to the apps directory, then enabled the app as admin in the web interface. I attempted to go the cloning of the git hub site, have never done that and I couldn't find any clear instructions on how to do that. I'd be interested in using git hub some day in that manner, just have no idea what I'm doing.
Bookmarks app is back in business.