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Migrating Firefox to a New PC

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I have an older laptop and got a new one. I have installed Firefox 89.0 on both machines. I want to migrate all of the Firefox data from the old one to the new one. I have copied the Profile from C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles to a thumb drive. I believe this to be all that I need to move to the new machine. The problem is that I don't know where to put it on the new machine.

I understand that Firefox must be closed when I modify the new machine. I also discovered that there is a Profile.ini file that has a pointer to the filename that Firefox will use when it is opened. Do I have to modify this file as well?

Perhaps I am on the wrong track and need to be redirected. If so, please point me to an article or wiki that will put me on the right one.

Chosen solution

Hi rabbit, I think you may over thinking this issue.

What i suggest is to get on the old laptop and sync FF to your FF account. After the sync ends, which is when "sync now" is cited, log out of the FF account.

Now go back to the new laptop, open FF and log into your account. When you execute sync, the uploaded data will download to the empty profile.

Afterwards log out and youre done.

caveat: if you have never done a sync before, then the above is a good methodology. However, if you are not sure if you have ever sync'd, then create a black empty virgin profile from any computer, log in and execute a sync. Utilize the temporary blank profile to reveal what you may or may not have in the sync account.

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Helpful?

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You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.


You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.


  • bookmarks and history: places.sqlite
  • favicons: favicons.sqlite
  • bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
  • cookies.sqlite for the Cookies
  • formhistory.sqlite for saved autocomplete Form Data
  • logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
    key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
  • cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
  • persdict.dat for words added to the spell checker dictionary
  • permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
  • sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Helpful?

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Thank you for the response, cor-el!

The information is helpful; however, what I need to know specifically is what to do on the target machine.

I've tried countless combinations of copying data and removing profile data existing on the target machine without success.

Do I need to edit the profile.ini file on the target machine? Is there a profile.ini on the source machine within the profile data? (I've not found one.)

You say that it is best not to copy the entire profile folder. Experience tells me this is true. I shall try your suggestion of copying selected folders you identified. I infer that doing so will overwrite thus displacing files of the same name on the target machine? .. .

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Chosen Solution

Hi rabbit, I think you may over thinking this issue.

What i suggest is to get on the old laptop and sync FF to your FF account. After the sync ends, which is when "sync now" is cited, log out of the FF account.

Now go back to the new laptop, open FF and log into your account. When you execute sync, the uploaded data will download to the empty profile.

Afterwards log out and youre done.

caveat: if you have never done a sync before, then the above is a good methodology. However, if you are not sure if you have ever sync'd, then create a black empty virgin profile from any computer, log in and execute a sync. Utilize the temporary blank profile to reveal what you may or may not have in the sync account.

Helpful?

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You can use the button on the about:support page to go to the current profile folder and copy the files with your personal data from the backup to that profile folder to replace existing files. Make sure that Firefox is closed when you replace the files.

Helpful?

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·´¯`·...¸>-)))º> ~dbben (databaseben),

Thank you very much!!!!

I've been using Firefox for decades and did not know about the Sync feature despite having seen it in the Settings many times.

Most helpful. Thank you again and again.

Helpful?

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You're welcome.

We are glad to be of help.  :-)

btw: keep your FF sync account closed on both machines; until those absolute moments when you are ready to sync.

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