Entering Safe Mode in a program is a method of starting the application fresh, without custom modifications that have made since it was first installed. The purpose of such a launch is to help identify what may be causing a crash, hang, or general instability.

Lots of programs have their own built-in mechanism for launching in Safe Mode. We’re going to look at 4 popular programs and what their triggers are for opening in Safe Mode.

Start Thunderbird in Safe Mode


Safe Mode in Thunderbird temporarily affects the following:

  • All extensions are disabled.
  • The default theme is used, without a persona.
  • The Just-in-time (JIT) JavaScript compiler is disabled.
  • The userChrome.css and userContent.css files are ignored.
  • The default toolbar layout is used.
  • Hardware acceleration is disabled.

However, the following are not modified in Safe Mode:

  • The status of plugins is not affected.
  • Custom preferences are not affected.

How to Run Safe Mode in Thunderbird

Open the “Run” dialog box with “Windows Key + R.” Enter “thunderbird –safe-mode” to launch Thunderbird in Safe Mode.


The following window will appear, where you can permanently disable all the add-ons and/or reset the toolbars, or just continue in Safe Mode to diagnose issues with the temporary changes listed above.


Start Outlook in Safe Mode


There are two types of Safe Modes in Outlook. The first is called Automated, the second User-initiated. An Automated Safe Mode occurs during startup of the program. A notification will indicate if a problematic add-in or extension was found. But Outlook can be started in Safe Mode manually, in a User-initiated manner, to help troubleshoot issues.

Safe Mode in Outlook temporarily affects the following:

  • No templates can be saved.
  • In Microsoft FrontPage, the last used Web site is not opened.
  • The Office Assistant is not automatically displayed.
  • Toolbar or command bar customizations are not loaded and customizations cannot be saved.
  • The AutoCorrect list is not loaded and changes are not saved.
  • Recovered documents are not automatically opened.
  • Smart tags are not loaded and new tags cannot be saved.
  • All command line options are ignored except “/a” and “/n”.
  • Files cannot be saved to the Alternate Startup Directory.
  • Preferences cannot be saved.
  • Additional features and programs will not automatically load.
  • Documents with restricted permission cannot be created or opened.

How to Run Safe Mode in Outlook

There are two common ways of doing this. Hold down the “Ctrl” key while opening Outlook to get the following prompt, asking if you want to start it in Safe Mode:


Alternatively, open a “Run” dialog box and enter “outlook.exe /safe.”


This command will work for 2010 or 2013 Outlook, whichever is installed.

Start Firefox in Safe Mode

Maybe many add-ons have been recently installed, the browser crashed a several times in one week, or some other related issue. Start Firefox in Safe Mode to help identify if your own modifications are what are instigating the issues.

Safe Mode in Firefox temporarily affects the following:

  • All extensions will be disabled (but this will not reset any preferences that some extensions may modify).
  • Firefox will be using the default theme.
  • Default toolbar settings and controls will be used.

Open the “Run” dialog box with “Windows Key + R.” Enter “firefox –safe-mode” to launch Firefox in Safe Mode.


Upon running the above command, Firefox will show the following prompt.


Take caution not to completely reset your settings, but instead choose “Start in Safe Mode” to temporarily disable add-ons and custom settings.


Note that plugins are not disabled in Safe Mode, but only the features contained in the “Extensions” and “Appearance” sections.

Start Chrome in Safe Mode

If Chrome is causing issues, starting without any extensions enabled may help troubleshoot where the problem lies.

Open the “Run” dialog box with “Windows Key + R.” Enter “chrome.exe –disable-extensions” to launch Chrome in Safe Mode. Safe Mode in Chrome is done by simply disabling all the extensions, which is sometimes where a critical problem may lie.

Note: There are double hyphens before the word “disable” in this command, like this screenshot indicates:


The “Extensions” menu item is actually inaccessible because Safe Mode completely disables every extension.


Final Thoughts

Once you’re in Safe Mode, if everything is working properly, then whatever plugins or extensions the program has temporarily suspended when launched could very well be the issue. Take the time to identify each and every aspect of what was disabled to help identify what the problem could be.