I'm categorizing a lot of images and for this I use the search engine at Commons. At some point I noticed the search sometimes took a while and than returned "There were no results matching the query.". After one or more reloads of the page, the search would return the expected results.
I see two things here:
- A timeout problem. Is the Wikimedia search backend overloaded?
- Incorrect handling of timeouts. If a timeout occurs, the search interface should mention that and not throw "There were no results matching the query."