Safe Mode
- This article applies to Firefox and Thunderbird.
This article also applies to SeaMonkey 2.0 and above.
Safe Mode is a debugging startup mode where all added extensions are disabled, the default theme is used, and default localstore settings (toolbar settings and controls) are used. Starting in Firefox 3.5, the new Just-in-time (JIT) JavaScript compiler is also disabled.
Note, however, that any changes made to preference settings remain in effect and all available plugins are used (bug 342333). In Firefox 3.5 and below, any changes made via userContent.css and userChrome.css remain in effect (bug 333808, fixed in Firefox 3.6).
In Firefox, Safe Mode includes a number of troubleshooting options that allow you to make changes upon browser restart, such as disabling all add-ons or resetting preferences. (see below).
Starting Safe Mode
To enter Safe Mode you must first make sure Firefox/ Thunderbird/SeaMonkey is not running in the background. This includes all windows like the Download Manager and Extensions that open in a separate window.
Windows
Use one of these methods to start your Mozilla application in Safe Mode. This should not be confused with restarting the computer in Windows Safe Mode!
- Use the "Mozilla Firefox (Safe Mode)", "SeaMonkey (Safe Mode)", "Mozilla Thunderbird (Safe Mode)", or "Mozilla Thunderbird (No Extensions)" shortcut in the Mozilla Firefox, SeaMonkey, or Mozilla Thunderbird program folder on the Windows Start Menu.
- Starting in Firefox 4 (4.0b8pre and above): Hold down the Shift key while double-clicking the Firefox icon. [1]
As an alternate method, you can start in Safe Mode by selecting "Start -> Run" (on Windows 7/Vista, enable the Run box, as described here) and entering,
For Firefox, one of these:
firefox -safe-mode
"C:\Program Files\Mozilla Firefox\firefox.exe" -safe-mode
- (For 64-bit Windows)
"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -safe-mode
For Thunderbird, one of these:
thunderbird -safe-mode
"C:\Program Files\Mozilla Thunderbird\thunderbird.exe" -safe-mode
- (For 64-bit Windows)
"C:\Program Files (x86)\Mozilla Thunderbird\thunderbird.exe" -safe-mode
For SeaMonkey, one of these:
seamonkey -safe-mode
"C:\Program Files\SeaMonkey\seamonkey.exe" -safe-mode
- (For 64-bit Windows)
"C:\Program Files (x86)\SeaMonkey\seamonkey.exe" -safe-mode
Adjust the path accordingly based on the actual installation directory (e.g., on 64-bit Windows, use "Program Files (x86)" instead of "Program Files") or if you installed your Mozilla program in a different location than shown above.
Linux
On Linux, you can go to your Terminal and run (for Firefox):
/path/to/firefox/firefox -safe-mode
Mac OS X
On Mac OS X, hold the Option key while starting your Mozilla application. [2] If this does not work:
Go to Utilities (in the Applications folder) and open Terminal, then run (for Firefox):
/Applications/Firefox.app/Contents/MacOS/firefox-bin -safe-mode
For Thunderbird, this is the line to run in Terminal:
/Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin -safe-mode
If you have installed the application to another location, modify the path as such. It's the "-safe-mode" command line parameter that's crucial here.
How to know you are in Safe Mode
Thunderbird and SeaMonkey 2
- All extensions will be disabled. You will still be able to select them in the Add-ons/Extensions list but only for the purpose of upgrading or uninstalling (the options button will be disabled).
- Default toolbar settings and controls will be used.
- The default theme will be used.
Firefox
- A window called Firefox Safe Mode with some troubleshooting options appears.
At that point, you can either continue to Safe Mode or select some troubleshooting options and restart Firefox in normal mode to apply the changes.
If you choose to continue in Safe Mode:
- All extensions will be disabled (but this will not reset any Firefox preferences that some extensions may modify).
- Firefox will be using the default theme.
- Default toolbar settings and controls will be used [3].
If you choose any of the troubleshooting options, the changes are only applied if you choose Make Changes and Restart.
Safe Mode options in Firefox
When you select any of these options and choose the "Make changes and restart" button, Firefox will restart in normal mode and the selected changes will be made. [4]
- Disable all add-ons - Disables all themes and extensions; starting in Firefox 3.5, this option also disables all installed plugins. [5] You can use "Tools -> Add-ons" to selectively re-enable them when you restart Firefox (details here).
- Reset toolbars and controls - Removes any toolbar customizations you may have made via the "Customize Toolbar" dialog. Also restores default window size/position and tree sort order and resolves various localstore corruption issues.
- Reset bookmarks to Firefox defaults (Firefox 3.5 and below) or Delete all bookmarks except for backups (Firefox 3.6 and above [6]) - Replaces your bookmarks with Firefox defaults (your browsing history is left intact). Caution: If you select this option and want to undo the change will need to restore your bookmarks from backup.
- Reset all user preferences to Firefox defaults: - Resets any user-set preferences to the default values (except for those set in the optional user.js file) and restores the default theme. Does not affect any userChrome.css or userContent.css changes.
- Restore default search engines - Adds back all of the default search engines (currently Google, Yahoo, Amazon.com, Answers.com, Creative Commons, eBay, and in Firefox 3, Wikipedia) if some are missing. It does not remove any added search engines.
Buttons
- Make Changes and Restart - This restarts Firefox in normal mode and applies the changes in any of the options selected above.
- Continue in Safe Mode - Starts Firefox in Safe Mode (this will not apply any of the options selected above).
- Exit
See also
External links
Related bug reports
- Bug 303279 - Safe Mode: Use "safe" localstore
- Bug 304403 - better safe mode UE
- Bug 311466 - {mac} Open app in safe-mode if the option key is pressed during startup
- Bug 333808 - safe mode should disable userContent.css and userChrome.css (Fixed in Firefox 3.6)
- Bug 342333 - Safe mode should disable plug-ins
- Bug 409959 - Safe mode option to disable all add-ons doesn't disable plugins (Fixed in Firefox 3.5)
- Bug 453642 - Safe mode should disable JIT (Fixed in Firefox 3.5)
- Bug 478846 - Safe mode should not disable JIT
- Bug 602562 - Add keyboard modifier to start in safe mode for windows (Fixed in Firefox 4)