Rated 5 out of 5 stars

I, too, am a long time user of Session Manager, and very upset that Firefox 57 will not allow its use. I have come to depend on it for loading previous sessions saved over a large timescale. No other extension offers the same flexibility and I would be lost without it.

Alas, until and unless the folks at Mozilla update the necessary API's (Application Programming Interfaces) that Session Manager uses, the developer cannot make his extension compatible with Firefox 57+.This MAY happen but it may take time. It's Mozilla's fault, not his!

Meanwhile you can block the upgrade to FF57 and carry on using FF56 (at risk of security vulnerabilities) or download & install Waterfox (it's only available in 64 bit) or Firefox ESR ( https://support.mozilla.org/en-US/kb/switch-to-firefox-extended-support-release-esr ) which will allow you to use the old extensions (including Session Manager) for a few months longer

You can also sign up for an account with Bugzilla, the forum for the developers of Firefox, and vote for these API's to be sorted out.

Website is: https://bugzilla.mozilla.org/ and the API's to vote on are:

https://bugzilla.mozilla.org/show_bug.cgi?id=1378651
https://bugzilla.mozilla.org/show_bug.cgi?id=1381922
https://bugzilla.mozilla.org/show_bug.cgi?id=1378647

Please follow Bugzilla etiquette, and just vote for the bug without commenting. Comments like "you need to fix this!" aren't helpful. Leave the comments to the experts.

Let's all hope to see Session Manager back in the new Firefox soon!

This review is for a previous version of the add-on (0.8.1.13).