Over the past 7 days, there have been around 99419 hits on the "too-many-titles-for-query" deprecation warning from user agents starting with "WikipediaApp", for example "WikipediaApp/2.4.184-r-2016-12-14 (Android 6.0.1; Phone) Google Play". For those with access to Kibana, see [[https://logstash.wikimedia.org/goto/4ced45460a793ed4a1182b165215cc05|this dashboard]].
For most users,[1] a maximum of 50 titles may be specified for the `titles` parameter. Titles in excess of 50 are ignored with a warning, although someday I'd like to make that an error. If you have more than 50 titles to query, you should query them in batches. This limit applies to other multi-valued parameters as well.
The queries being made seem to mostly resemble `action=query&format=json&titles=...&continue=&prop=pageimages%7Cpageterms&piprop=thumbnail&pithumbsize=320&pilimit=...`
[1]: Users with the apihighlimits right have a limit of 500 rather than 50.
==== API call tasks that need updating ====
[] ReadingListPageInfoTask (extends PageQueryTask) //<-- this appears to be our culprit w/r/t the warnings//
[] GetDescriptionsTask (needed only by DisambigListAdapter)
[] PageImagesTask (needed by DisambigListAdapter, and by PageDataClient but only for a single title)