From MozillaZine Knowledge Base

This article deals with Firefox closing unexpectedly, or closing after an error dialog (e.g., the Mozilla Crash Reporter) appears.

• If Firefox hangs, freezes, or stops responding to user input but does not close, see Firefox hangs.

If Firefox is crashing, first make sure you are using the latest public release version of Firefox, which will have the most recent fixes. You can download and install the latest version of Firefox from mozilla.com or you can use the Software Update feature from within Firefox. You may also wish to review the Firefox release notes for your Firefox version, to see if the issue and solution is listed under "Known Issues".

Crash logs may help you to locate the problem. See Crash reports, below.

Extensions

Problematic extensions may cause crashes. Start in Firefox Safe Mode and click "Continue in Safe Mode". This will help determine if an extension is causing the problem, since Safe Mode disables all extensions.

Note: If Firefox also crashes in Firefox Safe Mode, then an extension is not the problem and you should skip to the next section.

Run Firefox for awhile and if it no longer crashes, go to the Add-ons Manager Extensions list, click the Disable button for every extension, and restart Firefox normally. If the crashes no longer occur, one of your extensions was causing Firefox to crash.

If disabling all extensions and restarting Firefox in normal mode doesn't resolve the crash problem:

• In Firefox 4 and above, Safe Mode also disables hardware acceleration, so the problem could be a video driver issue (see below). You can test for this by turning off the Firefox setting to use hardware acceleration ("Tools -> Options -> Advanced / General").
• In Firefox 4 and above, Safe Mode also disables the JIT (JavaScript) compiler (JaegerMonkey). There have been crashes reported where the crash signature contains EnterMethodJIT [1]). If you have such a crash signature then try to set the javascript.options.methodjit.* prefs to false on the about:config page. [2] [3]

Other installed software

Other installed software that is running on your computer may be causing Firefox to crash, including:

McAfee SiteAdvisor

The SiteAdvisor component included with McAfee's Internet security software can cause Firefox to crash at startup. Even though it is installed as a Firefox extension, you may not be able to disable it from within Firefox Safe Mode. To resolve the problem, you can remove SiteAdvisor using the McAfee uninstaller (see McAfee's article, How to uninstall SiteAdvisor for details). [4] [5]

NVIDIA Network Access Manager

The NVIDIA Network Access Manager, an optional application for network security included with some NVIDIA products, can cause Firefox to crash unexpectedly. An easy workaround is to uninstall or disable this program and use another firewall, such as the built-in firewall included with Windows 7. [6] [7] [8]

Roboform

The RoboForm Password Manager application for Windows can cause Firefox to crash at (or close to) startup. If you use this application, download and install the latest version (7.6.2 or above) from the RoboForm for Firefox page or from http://www.roboform.com/download. [9] Note: RoboForm versions 7.6.1 and below are now blocklisted in Firefox 8 and above. [10]

Spector Pro for Windows

Spector Pro for Windows computer monitoring software can cause Firefox to crash at startup or when opening a new tab. If you use this product, try updating to the latest version or contact SpectorSoft Support. [11] [12] [13]

ThreatFire

PC Tools' ThreatFire anti-malware software can cause Firefox to crash at startup. Try updating ThreatFire to a newer version or uninstall it. [14] [15] Note: If you have both ThreatFire and Avast software installed, see this article.

Trusteer Rapport

Trusteer Rapport (an application promoted by some banks for malware protection) may cause Firefox to crash. If you use this software, try disabling it as follows: [16] [17]

• On Windows: Go to "Start->All Programs->Trusteer Rapport->Stop Rapport"
• On Mac: Go to "System Preferences -> Other -> Rapport -> Stop Rapport"

If that stops the crashes, try updating the software to the latest version, uninstall the program if you don't need it, or contact Trusteer Support. [18] [19] [20] [21] [22]

ZoneAlarm ForceField

ZoneAlarm ForceField (either standalone or included with ZoneAlarm Extreme Security) may cause Firefox to crash on certain websites or crash at startup. Try clearing the ZoneAlarm virtual cache (depending on ZA version, go to "Browser Security -> Settings -> Advanced" or "Internet -> Web Security -> Settings") then click "Clear Virtual Data" and restart Firefox. If you still have problems, turn off Forcefield (in ZA Extreme Security, go to "Internet -> Web Security -> Settings -> Advanced Settings", and turn off "Enable Virtualization"). [23] [24] Note: If Firefox fails to start after an update, see Firefox does not start after updating with ZoneAlarm ForceField enabled.

Crash when starting Firefox

Crashes that occur when starting Firefox are difficult to troubleshoot, especially if you also cannot start in Firefox Safe Mode. Make sure you allow the Mozilla Crash Reporter to submit a crash report so that you can view it later to get any useful information about the crash, including related bug reports (see viewing crash reports).

Note: If Firefox doesn't start up but you aren't sure whether it crashed or not and you didn't see the Mozilla Crash Reporter, see also Browser will not start up.

• Problematic extensions can cause Firefox to crash at startup, especially if compatibility checking has been turned off or if the extension is erroneously marked as compatible for your Firefox version. You can try starting in Firefox Safe Mode which disables all extensions. When you see the "Firefox Safe Mode" window, click "Continue in Safe Mode", go to the Firefox "Add-ons -> Extensions" list, disable all of your extensions and then restart Firefox. If Firefox starts normally, one of your extensions was causing the crash. [25]
• If Firefox opens without crashing in Firefox Safe Mode but still crashes after you disable all extensions and restart Firefox normally, the problem could be a video device or driver issue (see below) since Firefox Safe Mode disables hardware acceleration (Firefox 4 and above). Try restarting in Firefox Safe Mode and turn off hardware acceleration in Firefox Advanced settings (Options -> Advanced / General (tab)"). [26]
• Firefox can crash at startup if your Firefox program folder contains mismatched file versions. To resolve, reinstall Firefox. If the startup crashes persist, do a "clean reinstall" (remove the existing Firefox program folder, download the Firefox installer from mozilla.org with another browser, and then reinstall Firefox). [27] [28] [29]
• Crashes at startup can occur in Firefox 7 or above (but not Firefox 6 or earlier) if you are using a corporate login system such as IBM Tivoli Access Manager or Oracle Enterprise Single Sign On Manager (bug 680927). See the bug report for a suggested workaround (details here), apply the fix from Oracle (see bug comments 58-61) or downgrade to Firefox 3.6.xx (available here) which is still being maintained. Note that, starting in Firefox 10, the same bug causes Firefox to hang at startup, rather than crash, with the process running in the background consuming CPU. [30] [31] [32] [33].
• If Firefox also crashes when you try to start in Firefox Safe Mode but Firefox will start when you restart the computer in Windows Safe Mode, it's likely that other software installed on your computer that starts when Windows starts (or malware) is causing the crash. [34] [35] [36]
• Other software installed on your computer can cause Firefox to crash at startup, including:
  • McAfee SiteAdvisor component of McAfee's Internet suite (see above)
  • RoboForm (see above)
  • Spector Pro for Windows (see above)
  • ThreatFire (see above)
  • Trusteer Rapport (see above)
  • ZoneAlarm ForceField, either standalone or as part of ZoneAlarm Extreme Security, if it was enabled during a Firefox update (see above for solutions).
• Malicious software installed on your computer can cause Firefox to crash at startup. [37] [38] Even though you are running up-to-date security software, you should do a full system scan and check for malware.
  • See this article's section on Backdoor.Ulrbot.C for help removing certain malware-related files in Windows Safe Mode, using Mozilla crash report information. [39]
  • Malware is a likely cause if Firefox 6 crashes at startup, even in Firefox Safe Mode, with a crash signature of nsStandardURL::SchemeIs or nsSimpleURI::SchemeIs but does not crash if you downgrade to Firefox 5 (or below) or upgrade to Firefox 7. [40] [41] Important: Even though the crashes no longer occur in Firefox 5 (or below) or Firefox 7, your computer is still compromised and you should remove the malware. [42] [43]
• Plugins that run within the Firefox process, normally in older Firefox versions, can cause a crash at startup (see below).
• Missing system fonts can cause Firefox to crash at startup. [44] [45] [46] On Windows, run the System File Checker [47] to restore the missing fonts.
• Older versions of the Google Desktop application can cause Firefox to crash at startup. [48] Uninstall Google Desktop and then download and install the latest version. Note: This should no longer an issue in Firefox 3.6 and above because of the fix for bug 519357.

Crash when downloading

• Try clearing the download history (go to the "Tools" menu (or click the Firefox Button to open the menu) and click "Downloads" and "Clear List"). Alternately, delete the file "downloads.sqlite" from the Firefox profile folder. For more information, see Unable to save or download files#Clear_the_download_history.
• If Trusteer Rapport software is installed, try disabling it (see above).

Damaged plist file - Mac OS X

On Mac OS X, sometimes a recurring crash pattern is caused by a preference file being damaged. Quit Firefox, then go to your user Library -> Preferences, find the file "org.mozilla.firefox.plist" and move it to your desktop (don't trash it; just leave it on the desktop). When you restart Firefox, a new .plist file will be generated. If the new preferences file is working well, you can trash the .plist file on the desktop. More information on corrupt .plist files can be found here. [49]

Windows compatibility mode

On Windows XP, sometimes Firefox must be run in Windows 2000 compatibility mode. Right click on your Firefox desktop icon and click on Compatibility > change the setting to Windows 2000 > click Apply.[50]

Video drivers

Certain video devices or display drivers can cause crashes. Make sure your drivers are up to date. Starting in Firefox 4, details about your video device and driver can be found in the Graphics section of the Troubleshooting Information (about:support) page. Note: In Firefox 4 and above, turning off the option to use hardware acceleration ("Tools -> Options -> Advanced / General -> Use hardware acceleration when available") may prevent video-related crashes. [51] [52]

Hardware problems

Hardware problems, especially bad RAM chips, can cause Firefox to crash. [53] Download Memtest86 for Windows and Intel Linux or Rember for Mac to test if you have bad RAM chips.

Plugins

Note: In Firefox 4 and above, most plugins run in a separate "plugin-container" process by default and will not crash the browser. Instead, only the plugin will crash. See Plugin-container and out-of-process plugins for more information.

Plugins are programs that work within Firefox and allow you to experience multimedia content such as video, animation or sound. Plugins can crash within their own code or can cause a crash within Firefox code. Try updating your plugins to the latest versions, which you can do through Mozilla's plugin check. You can also temporarily disable your installed plugins to see if the crashes stop, either by disabling the plugin via "Tools -> Add-ons -> Plugins" (Firefox 3 and above) or by renaming or removing the associated plugin file. See Issues related to plugins for details on troubleshooting plugin issues.

• Java (Mac OS X) - On Mac systems with Java version "1.6.0_29" (Java SE 6 Update 29), Firefox 8.0 will crash after running a Java applet when closing the tab or hitting the back button. Fixed in Firefox 8.0.1 (bug 700835).

• RealPlayer - The RealPlayer plugin may crash the browser (bug 572801) or, in Firefox 4 and above, cause a plugin crash on sites with embedded RealMedia (bug 667399). You can disable the "RealPlayer(tm) G2 LiveConnect-Enabled Plug-In (32-bit)" in the Add-ons manager Plugins list to avoid such crashes. Note: Direct links to Real Media files (such as .ram or .rm links) can still be opened in the RealPlayer application itself, even though the plugin is disabled.

• VLC Media Player - If you are using the VLC Media Player mozilla plugin, Firefox may crash when viewing WMV media. The VLC Media Player browser plugin conflicts with the Windows Media Player plugin, so you need to disable the plugin or remove the VLC plugin file "npvlc.dll" from the Firefox installation directory plugins folder, for embedded WMV files to play properly.

• Hulu Desktop (Mac OS X) - Older versions of the Hulu Desktop web plugin can cause Firefox to crash on Mac OS X. If you can open Firefox, use the Add-ons manager ("Tools -> Add-ons -> Plugins") to disable the plugin. (Note: The web plugin is listed as "Hulu Desktop Support Plugin blah -de- blah" in the Firefox Add-ons manager.) [54] To resolve, either delete or remove the "huludesktop.webplugin" file to another location (e.g., move it from the /Library/Internet Plug-ins folder to the Disabled Plug-ins folder) or else download and install the latest version of Hulu Desktop to update the plugin. [55] [56] [57] [58] [59]

• WebEx (Mac OS X) - The WebEx plugin can cause Firefox to crash (or hang) at startup. To resolve, either delete the "WebEx.plugin" file or disable the plugin by moving it to another location. Note: The "WebEx.plugin" file is located in the ~/Library/Internet Plug-ins folder (Macintosh HD/Users/<user account>/Library/Internet Plug-Ins) instead of in the more typical root directory /Library/Internet Plug-ins folder, where other Internet plugins are installed. [60].

• Plugins installed by malware - If you have malware installed on your system, it can include a plugin file that causes Firefox to crash. For example, on Windows, "NPFFAddOn.dll" would cause Firefox to crash at startup, resolved in Firefox 3.6 and above [61] [62] [63] See Issues related to plugins for more information on detecting and disabling installed plugins and make sure you also check for malware.

Still experiencing problems?

• The standard diagnostic may resolve crashes not specifically mentioned in this article.
• Check for viruses, spyware and other malicious software.

Crash reports

Mozilla Crash Reporter crash reports may help you locate the problem (see the linked articles for detailed information). For help analyzing the crash information, post on the Firefox Support forum with your Report ID and what steps cause Firefox to crash. Those who read your post may be able to look up your crash and find an existing bug report or file a new one for you. Also, if the crash you experience is common, it may be marked as a "topcrasher", making it more likely to be fixed in the next Firefox release.

Your operating system's system log may also have a crash report. The information will probably include the name of the module that caused the crash. On recent Windows versions, go to Start > Settings > Control Panel > Administrative Tools > Event Viewer. In the application tab, right-click on the event and select Properties. When you report the event, you should copy the information from the log.

External links

• Firefox crashes (Firefox Support)