Thanks again to @amyt and colleagues.
Beta 4.2.0a was released on 2017-10-12 and is:
- compatible with e.g. Firefox 56.0.1
- not compatible with Firefox 57.
Another beta, announced on the same day:
- has a version number that’s inferior (4.1.80.2beta at the time of writing)
- is described by LastPass as for Firefox 57
- is also compatible with Firefox 56.0.1:
(Ignore the 1970 date in that screenshot. It’s a cosmetic bug, unrelated to LastPass.)
4.1.80.2beta
From manifest.json
:
"strict_min_version": "52.0",
"update_url": "https://lastpass.com/ffwebext/firefox-update.json"
– but I do not intend to test with any 52.x extended support release (ESR).