How To: Fix Thunderbird failing to open HTTP / HTTPS links

If you recently upgraded Thunderbird to v52 onwards and all links in emails stopped working (i.e. clicking on a link doesn’t open them in your browser) then you can fix it like this:

  1. In Thunderbird, go to Tools | Clear Recent History and clear everything (this just removes your usage history, not any emails), then
  2. Close Thunderbird, go into your profile folder (i.e. where the emails are stored) and delete all the places.sqlite files.

Tap-tap. Job done.

Source: https://bugzilla.mozilla.org/show_bug.cgi?id=1354007