The update orphaning dashboard[1] shows that over 8% of users who are more than two version out-of-date are reporting a value of CHK_ADDON_NO_INCOMPAT for UPDATE_CHECK_CODE_NOTIFY. This value should only be reported when a Firefox install first discovers that an update is available. We should verify that this is the case and understand if there is truly such a large number of users who are only just discovering an update when they're already two versions behind. [1] https://telemetry.mozilla.org/update-orphaning/

Is this still valid Stephen? Looking at the current report, I didn't find your 8% chunk.

The update orphaning dashboard is now handled by mhowell. Forwarding n-i.

First, I'm changing the summary because we got rid of the addon compatibility check back in bug 1262880 and this check code was renamed. We are still getting quite a few of these pings though, it's actually 13.8% for last week according to the dashboard. This code means that we found an update and started trying to download it, but that download is still in flight, it hasn't either succeeded or failed yet. These clients should therefore be making it into the download code portion of the dashboard, in the "no ping" category. I'm not sure there's anything really actionable with just this check code.