A recently deployed change to Recommendation-API had to be rolled back because list=mostviewed started returning zero results after midnight UTC today, causing an endpoint check to alert on an unexpected 404 response (T216750#5508340).
A zero-result response from list=mostviewed seems like a bug because the PageViewInfo code takes steps to work around the normal AQS pageviews processing delay, and because there's no indication in the API docs that a zero-result response is to be expected.
Steps to Reproduce:
- Request https://en.wikipedia.org/w/api.php?action=query&list=mostviewed
- I'm assuming this will start providing results at some point today. It might depend on requesting at shortly after midnight UTC.
Actual Results: zero-page result
Expected Results: nonzero-page result