First, create a new profile as the current may have incompatible files.

https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer Sync your bookmarks, history, passwords, add-ons and open tabs with another copy of Firefox. Learn how to set up Sync.

https://support.mozilla.org/en-US/kb/how-do-i-choose-what-types-information-sync-firefox We'll show you how to choose which types of information (bookmarks, history, add-ons, and passwords) to share across all your devices through Firefox Sync.

https://support.mozilla.org/en-US/kb/firefox-sync-troubleshooting-and-tips

https://support.mozilla.org/en-US/kb/sync-firefox-bookmarks-and-browsing-history-iOS Sync your passwords, history, tabs and other browsing information across your iOS, Android and desktop computers with Firefox Accounts.

You can transfer bookmarks via a JSON or HTML backup with a removable USB drive. A JSON backup includes more information, but both do not include the favicons.

• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
• https://support.mozilla.org/en-US/kb/import-bookmarks-html-file

Transferring logins might best be done via Sync like posted above if you can't achieve this via logins.json and key4.db in the main profile folder.

Firefox uses two locations for the Firefox profile folder, so make sure to look in the correct location. Location used for the main profile that keeps your personal data (Root Directory on about:profiles).

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>

Location used for the disk cache and other temporary files (Local Directory on about:profiles).

• C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>

Thanks for the replies. I don't need to "sync" across multiple devices, with the data (apparently) being stored or otherwise processed through another site. I only need to do this once, not on an ongoing basis. SURELY there is some way I can just COPY AND PASTE the data from the original install to the new one. Also, concerning local and roaming, the new ESR install actually has THREE profile locations; Local, Local Low, and Roaming. I had been told elsewhere that I only needed to be concerned about Roaming, is that not correct? And what about "Local Low?"

I've used the HTML process for bookmarks before, it did transfer them, but very klunky, and it didn't set up the bookmarks toolbar at all, had to manually do that. This seems so unnecessarily fiddly and complicated. Thanks again for the input, if anyone has any more suggestions, please pass them on.

Also, FredMcD, you mention "first setup a new profile." Do you mean in the old install, or the new one?

It is always a problem if you transfer data between different older and newer Firefox versions because files may not be compatible or you lack features. For bookmarks there always has been the bookmarks HTML backup. A bookmarks JSON backup might work as well, but importing in a different Firefox version isn't guaranteed. Transferring logins is usually most difficult because they are stored encrypted even if you do not use a primary/master password. Only Firefox 80 and newer versions have password import. On older versions there are possibilities to use code in the Browser Console to export and import login data in JSON format.

• /questions/1278039 How to print out my passwords in Firefox? I need to migrate user names and passwords for various web sites to a new computer