http://rest.wikimedia.org/de.wikivoyage.org/v1/page/html/Alice%20Springs returns HTTP 200
http://rest.wikimedia.org/de.wikivoyage.org/v1/page/html/Alice_Springs returns HTTP 404
The whole Mediawiki setup deals indifferently with ' ' and '_' in article title and IMO RestBase should too. This problem is a little bit annoying for script developers.
RESTBase actually normalizes spaces to underscores, so ought to return the same value. My first request with underscore did elicit a Cassandra backend error rather than a 404. A subsequent request with undescore succeeded.
I confirm this, currently the rest cache system does not act consistently and is not reliable at all (time to time requests fail/succeed).
@Kelson, logstash and graphite also showed elevated request error rates, which I tracked down to what looks like a schema disagreement among the cassandra nodes. After a rolling restart of Cassandra nodes things seem to be back to normal again.
While things are working again, this issue does serve to remind us to really wrap up T78514 with alerts for at least error rates and latencies.