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Adding actions for file extension on application in settings

  • 6 replies
  • 1 has this problem
  • 10 views
  • Last reply by mmomalaysia

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Hello, my previous application settings was messed up after the latest automatic update, I attempted a refresh but all my previous extension on the application settings was lost, so whenever I click a file ie Zip, rar not on the list it will save only instead of having the option of open.

How may I add back the extension association to a particular application in firefox?

Previously it will automatically detect the default applications to file type in Windows.

Please don't suggest the restore old profile method, done that and didn't work. Refresh and reinstall also been done.

Hello, my previous application settings was messed up after the latest automatic update, I attempted a refresh but all my previous extension on the application settings was lost, so whenever I click a file ie Zip, rar not on the list it will save only instead of having the option of open. How may I add back the extension association to a particular application in firefox? Previously it will automatically detect the default applications to file type in Windows. Please don't suggest the restore old profile method, done that and didn't work. Refresh and reinstall also been done.
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All Replies (6)

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You can possibly copy handlers.json from the profile saved to the "Old Firefox Data" folder on the desktop to the current profile folder created due to the reset.

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 (Root directory).

In Firefox 97 and 98+ there have been changes to the download panel.


You can set this pref to false on the about:config page to prevent opening the download panel on each download.

  • browser.download.alwaysOpenPanel = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.


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)
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cor-el said

You can possibly copy handlers.json from the profile saved to the "Old Firefox Data" folder on the desktop to the current profile folder created due to the reset. 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 (Root directory). In Firefox 97 and 98+ there have been changes to the download panel.

You can set this pref to false on the about:config page to prevent opening the download panel on each download.

  • browser.download.alwaysOpenPanel = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.


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)

Thank you, but I already mentioned the old profile method doesn't work, it is no good anymore.

Is there a way for the browser to detect associated file extension types as in Windows and so I can add in actions later in application settings?

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The only way to add an item under "Settings -> General -> Applications" is via "Always Open Similar Files" in the context menu in the download panel or in the Downloads Manager (Library).

See "Adding download actions":

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cor-el said

The only way to add an item under "Settings -> General -> Applications" is via "Always Open Similar Files" in the context menu in the download panel or in the Downloads Manager (Library). See "Adding download actions":

Unfortunately this option didn't show up as I tried a file. Would the add-on "Content-Type Fixer by jscher2000" help? I see that this add-on wasn't monitored for security

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The file type showed up in application option after I installed the "Content-Type Fixer by jscher2000" add-on. I'll keep this topic open for another day to see if there is other option available before closing.

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Another question, when "opening" file action is selected; how to set the action into opening file from the "appdata/local/temp" folder?