Do you still have access to all of your Firefox 43 settings files? Because Firefox 48 (or Firefox 52 ESR for XP) might be able to use the old logins file immediately if you swap a couple files, and Firefox 66 (for Windows 10) might be convinced to use them. You would be looking for this pair of files: * '''logins.json''' * '''key3.db''' Can you find any of those files in the old profile folder? The easiest way to access that folder is from inside Firefox while it is running, through the Troubleshooting Information page. Some references: * [[Profiles - Where Firefox stores your bookmarks, passwords and other user data]] * [[Recovering important data from an old profile]] Note: Recent versions of Firefox use '''key4.db''' so getting them to read an old logins.json + key3.db will require removing the key4.db file from the new profile. I think there are other threads with more detailed instructions.

''cadetson [[#question-1253625|said]]'' <blockquote> ... New machine will only import HTML file. ... </blockquote> That is for Bookmarks - only - never used by Firefox for passwords / logins.