After updating to owncloud 5.0.11 I got the following error in my Owncloud News Reader:

(For Google: A Toast saying „End of input at line 1 column 1“)

In my owncloud instance, I got an error in the administrator menu saying:

SQLSTATE[HY000]: General error: 1 no such column: feeds.articles_per_update at db.php#391

I updated the owncloud instance and app framework/news app but it still showed me that everything was uptodate, even when 5.0.12 was released. Via phpMyAdmin I could see that the feeds were still in the database but I couldn’t see them in the web app or Android app. So I just deleted the owncloud folder, downloaded the new .tar.bz2 from owncloud.org, removed the oc_news tables(do not delete e.g. the contacts or bookmarks!). Then I changed my username in oc_users, used my old username as my new username and reinstalled owncloud, this time version 5.0.12.  I could then delete the old (changed) username via the admin panel.

This is the third time I had to reinstall owncloud, because the update mechanism didn’t work properly… And yes, as advised, I did deactivate the news app and app framework for the update process 😉

I just had a look at the SQL-statements from my last backup and saw that articles_per_update is supposed to be a column in oc_news_feeds in the new version of the news app. Somehow, the owncloud update process didn’t update the news app or didn’t trigger a 3rd-party update process. Anyways, I guess this could also be solved by just adding this column manually:
`articles_per_update` bigint(20) NOT NULL DEFAULT '0'