User Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 Build ID: 20180118122319 Steps to reproduce: Download of Windows XP v52.6.0 version fails. URL: https://download-sha1.allizom.org/?product=thunderbird-52.6.0-SSL&os=win&lang=en-GB (this URL is only offered in a Windows XP environment) Firefox complains about the Certificate & then offers a v38.5.0 Download! https://download-sha1.cdn.mozilla.net/pub/thunderbird/releases/38.5.0/win32/en-GB/Thunderbird%20Setup%2038.5.0.exe IE doesn't complain about the Certificate, but offers the same Download. P.S. Couldn't find a suitable Version for the Bug Report: does "nn Branch" have any relation to Version? What on earth does "untriaged" mean? Try to find some terminology people understand. Actual results: Aborted download of incorrect version. Expected results: Windows XP v52.6.0 download.

The download system is intentionally and correctly forcing XP users to an older version of Thunderbird as implemented by 1240511. This is because of XP security issues related bug 1079858. https://support.mozilla.org/en-US/kb/get-latest-version-thunderbird-windows-xp-vista speaks to this. Same deal for Firefox > What on earth does "untriaged" mean? Try to find some terminology people understand. https://bugzilla.mozilla.org/describecomponents.cgi?product=Thunderbird&component=Untriaged#Untriaged