Impact: banner doesn't display, error is thrown
Volume: 22,438 errors per 24hrs (note we call UBN on errors over 1000)
https://logstash.wikimedia.org/goto/13d2bf0e26ba4399a9b1dedbac0e49d3
Applies to logged in users (Luckily I caught this one as I have a special user script alerting me to such errors):