I sent a debug with ID D545846133

Legacy add-ons are not disabled in Firefox 55; they are just marked as legacy. Either you misunderstood the message there or you're using an alpha version of Zotero (legacy extensions will no longer …

But why can't you open Zotero in Firefox? Again, Zotero for Firefox is still compatible with Firefox 55 — nothing has changed on that front yet. Firefox 57 will require that new Zotero Connector for …

As far as I know the Firefox 55 update shouldn't have changed anything, other than showing that Legacy badge in the Add-ons pane.

Waterfox/54.0.1

Not sure what your point is. Honestly, this is waste of time — please take the time to read my messages and, if you have a concern or don't understand something, take the time to write it out. Who is…

Also, Coolviews is kaput for any version above 42.0.

No, you're mistaken here. Legacy Firefox extensions — like Zotero for Firefox, and all of those — still work with Firefox 52 ESR, and will be supported until Firefox 57. And if you run Firefox 52 ESR…

using the Firefox-embedded version is just not an option going forward. It will stop working some time this year (probably mid-November) as Firefox disables the extension framework it relies on.