Fix Incomplete Firefox Profile Import from Windows to Mac

Firefox's import wizard is built for pulling data out of other browsers, so a Windows-to-Mac move usually lands with gaps: missing logins, dead extensions, and settings that never arrived.

Start with Firefox Sync. If pieces are still missing, export bookmarks as a file, copy logins.json and key4.db, then reinstall extensions by hand. Copying the whole profile folder is the last resort.

In this guide, I have covered:

Why your Firefox data looks half-moved after Windows to Mac

You copied things over, opened Firefox on the Mac, and half of it is missing. That is normal, and it is not a bug in your setup. Firefox’s built-in import wizard is built for pulling data from other browsers, such as Chrome, Edge, or Safari.

Point it at another Firefox installation and it copies only what it recognizes as browser-managed data. A few items slip through.

The usual stragglers: saved logins (they need a matching key database), extensions (official Mozilla Add-ons usually sync, third-party and sideloaded ones do not), form autofill data, site permissions, security certificates, and custom preferences in about:config.

The fixes below layer on each other. Pick the first one that solves your case and stop there.

Try Firefox Sync first for the easiest transfer

If both computers can reach the internet, this is the shortest path. Sync keeps bookmarks, saved logins, history, open tabs, and most extensions aligned between devices.

Set Sync up on Windows first, then sign in on the Mac to pull the data down:

1. In Firefox on Windows, open the menu and click Settings.
2. Click Sync in the left column.
3. Click Sign In and use your Firefox account email (or pair the devices with a QR code).
4. Tick the boxes for Bookmarks, Logins and passwords, History, and Add-ons.
5. On the Mac, install Firefox if it is not already there, open the menu, and click Settings.
6. Click Sync, sign in with the same account, and wait a few minutes for the data to arrive.

If everything came across, you are done. If logins, extensions, or some settings are still missing, move to the next section.

If you do not want to create a Firefox account, skip Sync and use the bookmark export and import method below.

Export your bookmarks from the Windows Firefox

Bookmarks are the one category you can move by hand with almost no risk. Firefox’s Library saves them as a single portable file that holds every bookmark and folder.

HTML stays portable. JSON keeps more of the internal metadata, including tags and folder order.

Make the backup on Windows:

1. In Firefox on Windows, open the menu and click Bookmarks.
2. Click Manage Bookmarks at the bottom of the panel.
3. In the Library toolbar, click Import and Backup.
4. For full-fidelity data (including tags and folder order), choose Backup… and save the date-stamped .json file to your Desktop.
5. For a portable file you can open anywhere, choose Export Bookmarks to HTML… and save the .html file to your Desktop.

For a longer walk-through of the Windows side of this step, see the dedicated Export Bookmarks from the Mozilla Firefox browser guide.

Copy the saved file to the Mac (USB drive, AirDrop, email, or cloud storage) before continuing.

TIP: JSON backups are tightly tied to your Firefox profile version. If you also plan to copy logins, use HTML for safer portability.

Import the bookmark file into the Mac Firefox

On the Mac, Firefox opens the same Library view and accepts the file you saved from Windows.

1. In the Library, click Import and Backup in the top toolbar.
2. Choose Import Bookmarks from HTML… for an HTML export, or choose Restore then Choose File… for a JSON backup.
3. Browse to the file. Firefox exports usually have names like bookmarks.html or a JSON snapshot from the bookmarkbackups folder.
4. Select the file and click Open or Import.

After the import finishes, bookmarks appear in a folder named after the file (for HTML) or restore to their previous locations (for JSON). Open the Bookmarks menu to confirm the folders you expected.

You’ll know it worked when the folder count and order on the Mac match what you saw on Windows. If a folder is missing, re-export from Windows and import again before touching anything else.

Bring saved logins and passwords across too

Bookmarks are the easy part. Passwords are where most Windows-to-Mac moves stall.

Logins live in two files inside the Windows profile: logins.json (the list of saved credentials) and key4.db (the encryption key). Copy both files together and replace the matching files in the Mac’s profile folder.

This is the approach Mozilla documents for moving logins between profiles. Do it after the bookmarks step so the rest of the profile is fresh:

1. In Firefox on Windows, open the menu and click Help.
2. Click More Troubleshooting Information.
3. In the Application Basics section, click Open Folder next to “Profile Folder”.
4. Quit Firefox on Windows (Alt+F4 or close from the menu), then copy logins.json and key4.db to your Desktop or a USB drive.
5. On the Mac, open Firefox and use the same path ( menu, Help, More Troubleshooting Information) to open the profile folder.
6. Quit Firefox on the Mac (Cmd+Q).
7. Drag the two Windows files into the Mac profile folder, replacing the existing logins.json and key4.db.
8. Reopen Firefox on the Mac and open Settings, then Privacy & Security, then Saved Logins to confirm the list is populated.

If a Primary Password is set on Windows, Firefox asks for it the first time you reveal a saved password on the Mac. Use the same password you had on Windows.

ALERT: If a Primary Password is set and you forget it, there is no way to recover the logins. Confirm you remember it before replacing the key database.

Reinstall extensions and review other customizations

Extensions are the part people notice first. Most add-ons from the official Mozilla Add-ons site come back through Sync, but sideloaded extensions, themes, and several about:config tweaks do not transfer. Set those up again on the Mac.

What to look at on the Mac:

• Extensions: open the menu and click Add-ons and Themes. Anything listed as installed but grayed out needs to be re-added or turned back on.
• Site permissions and tracking protection overrides: re-grant any per-site toggles you had set on Windows.
• Custom about:config preferences: open about:config on the Mac and re-apply the switches you had on Windows.
• Search engine and homepage: open Settings, then Search and Home, to set the same defaults you used on Windows.

If your Windows setup had a stripped-down start page, you can remove unwanted content from the Firefox New Tab page again on the Mac.

Advanced: drop the full Windows profile into the Mac Profiles folder

When the wizard leaves gaps and Sync is not an option, copying the whole profile folder is the method that actually works. It brings bookmarks, logins, history, extensions, and preferences across in one go.

It also carries the highest risk of anything here. Back up the Mac profile first.

1. On Windows, open the menu, then Help, then More Troubleshooting Information, then click Open Folder to open your profile.
2. Quit Firefox on Windows.
3. Copy the entire profile folder (the one named like xxxxxxxx.default-release) to a USB drive, cloud storage, or your Desktop.
4. On the Mac, quit Firefox if it is open (Cmd+Q).
5. In Finder, click Go in the menu bar, hold Option, then choose Library.
6. Open the Application Support/Firefox/Profiles folder.
7. Rename your existing Mac profile folder by adding -backup to the end of its name.
8. Drag the Windows profile folder into the Profiles directory.
9. Open Firefox on the Mac; if a profile picker appears, choose the folder you just added.
10. Once the import looks right, you can delete the -backup folder from the Mac.

ALERT: Always quit Firefox on both machines before copying profile files. Firefox locks files while running. Copying mid-session produces a corrupt database, which makes Firefox refuse to start on the Mac.

If Firefox on the Mac opens the wrong profile after the copy, type about:profiles in the address bar and use that page to switch profiles or rename folders to match.

Verify what made it across on the Mac

Quick checks confirm the migration is complete. The same “Profile Folder” entry from the troubleshooting page shows which profile is in use.

1. Click the menu, then Help, then More Troubleshooting Information.
2. Confirm the path under Profile Folder matches the profile you expected.
3. Open Bookmarks, then Manage Bookmarks, and look for your folders and order.
4. Open Saved Logins from Settings, then Privacy & Security, and confirm a few known entries are there.
5. Open the History menu and confirm past visits are listed.
6. Open a few tabs you had open on Windows (with Sync on, they appear under Synced Tabs).

Once everything checks out, your Mac Firefox behaves like the Windows profile did.

RELATED: Fix Firefox Not Opening Web Pages from Bookmarks