Developer reply by Julian Fitzell
Rated 5 out of 5 stars
Would be wonderful to see this addon updated for firefox 57+
Unfortunately Mozilla needs to implement new APIs in order to get this working in 57+. More details here: https://github.com/jfitzell/mozilla-keychain/issues/88
Feel free to add your voice to the relevant Bugzilla tickets:
https://bugzilla.mozilla.org/show_bug.cgi?id=106400
https://bugzilla.mozilla.org/show_bug.cgi?id=1344788
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