Live Chat troubleshooting guide | How to contribute

Live Chat troubleshooting guide

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This page documents common troubleshooting techniques that are used to solve some of the issues frequently asked in live chat. Most information needed to help users is documented in knowledge base articles. With any problem, try to find an answer before falling back to troubleshooting.
As a helper in Live Chat, you may encounter problems that you can't find information on. This page can help you find the cause of a problem, as well as help you fix problems after determining possible causes. Information learned while troubleshooting should be shared with others; you can post anything you learn in a related thread in the Contributors forum or discuss it in the community chatroom (in live chat, always discuss troubleshooting in the Contributors chatroom).
Some common support issues don't have documentation yet and need more information.

Common troubleshooting steps

With any issue, always search the knowledge base before attempting to solve the problem on your own. If an issue is not documented or you aren't sure what the issue is, using the troubleshooting steps on this page may help you narrow down the problem.

First things to try

Verify everything

It's important to understand exactly what a problem is before offering advice. It's important for the user to explain all symptoms and other problem details.

  • Ask questions: What exactly happens? What do you expect to happen? How often does it happen? What are you doing when it happens? Does it affect all websites? Did you install or update any other software?
  • Get a screenshot: If you aren't sure what's happening based on the user's description, ask for a screenshot.
  • Verify details of installed software: Actually check installed add-ons, the installed version of Firefox, the exact names/versions of any anti-virus software, etc
  • If there is an error, verify the exact text. Many error messages can be confusing, so verifying the exact text (or as much as the user can remember) helps with correctly identifying a problem. It's important to know the difference between an operating system error, a Firefox error page, and a javascript "alert()".

Verify exact behavior for lost/missing data issues (bookmarks, history, settings, cookies)

While verifying symptoms is important for all issues, it is especially important for issues involving data loss. Such issues include data being lost, data not being saved when Firefox is closed, and data unable to be changed.

  • It is useful to know where Firefox stores data, as corrupt or locked files often cause data storage issues.
  • Verify as many details as possible. Ask what is happening and what the user expects to happen.
    • Do data changes (new bookmarks, history items, back/forward button history, setting changes, new cookies) show up at all? Does an error result?
    • Does new data appear after closing and restarting Firefox?
    • Has the data loss occurred more than one time? When did/does it happen?
    • Are only some uses of data (eg. changing a certain bookmark or saving cookies on certain sites) affected, or are all uses of the data broken?
    • Which extensions are installed?

Check extensions

Many Firefox problems are caused by extensions. See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems for a guide on troubleshooting them, or try starting Firefox in Troubleshoot Firefox issues using Safe Mode.

Get crash reports

If the Mozilla Crash Reporter triggers and the user submits the report, looking up the crash ID is useful for solving the problem. For startup crashes, it is necessary to get the crash IDs manually. If Firefox runs, crashes can be viewed at about:crashes. See the Mozilla Crash Reporter article for details on obtaining crash reports.

  • If you aren't sure about a crash report, always ask! Many helpers and other community members can help investigate crash reports.
  • Many crashes are caused by software other than Firefox, such as Firefox extensions or malware. The Modules and Extensions tabs in the crash report can be useful in identifying possible causes of a crash.

Check security software

Some issues are known to be caused by various firewall and anti-virus software, especially issues with connecting to websites. If such an issue is reported, it's important to:

  • Ask for the exact name of all security software products installed.
  • Ask which version of each product is installed.
  • Find out when each product was updated and if it has expired.
    • Expired security software causing problems should be removed since it can't be updated.
  • All installed Firefox extensions - many security products install them.
  • Whether any security software has been uninstalled. Often, parts of uninstalled security software are left behind. If security software needs to be removed, uninstalling from Add/Remove Programs in Windows is always the safest method. If there are problems uninstalling, some companies offer a removal tool.
  • Tip: it can often help to obtain a list of running processes if you aren't sure which security software is installed.

Check Add-Ons and try Safe Mode

Extensions are the cause of many issues relating to broken websites or Firefox not working properly. If a user has extensions, we often ask the user to try reproducing the behavior with extensions disabled or in Troubleshoot Firefox issues using Safe Mode. For more information, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

Run Profile Manager

Firefox's Profile manager is used to create and modify Profiles - Where Firefox stores your bookmarks, passwords and other user data, each of which has unique bookmarks, preferences, add-ons, and data. (See where Firefox stores data.)

Reset localstore.rdf

The localstore.rdf file in the Profile Folder stores information about toolbars, window positioning, and other interface elements. If toolbar icons are missing, if there are strange problems with the browser interface, or if new windows open with the wrong size, resetting the localstore.rdf file can help.

Check the error and web consoles

If a feature (eg. bookmarks) is not working, or if a web application is broken, check the Error Console and Web console.

  • Look for errors about the specific feature that is not working. If part of Firefox is broken, look for NS_ERROR. If there is an error on a website, look for errors that include the misbehaving site.
  • Tip: Only check the Errors tab, as the default All tab contains many warnings which are not relevant.
  • Tip: If there are too many errors to look through, press Clear, then try using the broken feature again.

Problems on an individual website

If a certain website is misbehaving or producing error messages, an extension (eg. Adblock Plus), bad items stored in cache, or a bad cookie could be causing the problem.

  • First try clearing the browser cache, as problems can be caused when files are downloaded wrong or when outdated versions are stored. To clear the cache, use the Network tab in the Advanced panel of the Firefox options, preferences and settings. Press Clear Now to clear all items in the cache.
  • If the problem still occurs, check installed extensions. If you suspect that one of the extensions could be causing the problem, start Firefox in Troubleshoot Firefox issues using Safe Mode.
  • If the problem still occurs, a bad cookie could be causing it. In this case, the user needs to delete all cookies originating from the broken website.

Secondary methods

If you can't find a knowledge base article or issue to solve a problem, and the primary troubleshooting methods don't solve it, try these methods:

Clean installation

Some problems with Firefox are caused by a corrupt installation folder, by old files in the location folder, or by extra installed components. Performing a clean installation is a quick way to rule out these factors. All user data is stored in the profile folder, so performing a clean installation will not cause lost data.

  1. Close Firefox completely. (File->Exit on Windows/Linux, Firefox->Quit on Mac)
  2. Rename the Firefox installation folder or move it elsewhere.
    • Windows: This is usually C:\Program Files\Mozilla Firefox. "Mozilla Firefox" can be renamed to "Old Firefox"
    • Mac: This is usually Macintosh HD/Applications/ Macintosh HD/Applications can be opened in Finder, and Firefox can be dragged to Trash.
    • Linux: The install location varies based on distribution and installation method. Linux distributions usually don't put Firefox in its own folder, so this method can't be used.
  3. Download Firefox again from and install. (Installation instructions for Windows, Mac, Linux )
  4. If this fixes the problem, you can optionally check the old install folder for global extensions, components, or corrupt/locked files.

Try a new Firefox profile

Sometimes, the easiest way to get started with an issue that persists with Troubleshoot Firefox issues using Safe Mode is to create a new Firefox profile. The profile folder contains both extensions and numerous data files which can cause some issues; trying a new profile allows the issue to be narrowed down.

Clear Mac OS X system caches

Some issues with Firefox can be caused by bad data in the Mac OS X system caches. These include:

  • Firefox will not install due to a DMG mount error
  • Weird graphics issues in Mozilla applications
  • Certain font glyphs are messed up or wrong in Mozilla applications

Instructions to clear the caches:

  1. Restart the Mac in safe mode
    • To start in safe mode: Reboot, then hold down the shift button right after the Mac startup chime
  2. Restart the Mac normally

Suggest anti-spyware or anti-virus

If a problem with Firefox is being caused by malware, suggesting anti-virus or anti-spyware software can be helpful.

  • It is best to advise users of free-to-use software, rather than recommending specific software to purchase.
  • Mozilla doesn't recommend or endorse any specific products. Free-to-use products popular with the community include Avast Home, Spybot Search & Destroy, Malware Bytes, and Spyware Terminator.
    • Tip: Type sumobot malware in the Contributors chatroom for updated links to popular malware removal software
  • It is up to the individual helper to recommend specific software. Make sure that the user knows that software you recommend is your recommendation, not Mozilla's.

Obtain a list of running processes

When Firefox is not running, not connecting, or crashing, a list of running processes can be helpful. A popular utility to use for Windows is HijackThis:

  1. Download HijackThis from
  2. Run the utility, and choose to save a log file
  3. After generating a log, a user can paste it in the support forum or directly into live chat (HijackThis automatically opens the logfile in Notepad by default).

Obtain a list of modules in the Firefox process

Obtaining a list of modules in the Firefox process can help identify several problems, usually on Windows

There are two primary methods to obtain the list of processes:

  • Method 1: Use Listdlls (Windows only)
    • Listdlls is a Sysinternals application that can list running modules in any process without restarting it.
    1. Download listdlls from
    2. Extract listdlls.exe from; put listdlls.exe on the Desktop.
    3. Open the Run dialog (Go to Start...Run or hold down the Windows key and press R).
    4. type cmd and press OK.
    5. You will get to a command line. Type: cd Desktop.
    6. Press Enter/Return; the prompt will go to the next line. Type: listdlls firefox.exe > mozillabug.txt.
    7. Press Enter/Return again. A file called "mozillabug.txt" will be created on the Desktop. This file should be posted in the Contributors forum or pasted directly into Live Chat.
  • Method 2: Generate a crash report (all operating systems)
    1. Install the Crash Me Now extension.
      1. Download the XPI installer from - save the file to the Desktop
      2. Open the XPI with Firefox by dragging the file either to the Firefox icon or to Firefox's location bar.
      3. The Software Installation window will open. Choose to Install the add-on. Then, restart Firefox.
    2. After restarting Firefox, open the Tools menu and select Crash Me Now. Firefox will crash and the Mozilla Crash Reporter window will open. Submit the Crash report to Mozilla.
    3. Use about:crashes to obtain the newly created crash report.

Check for running Firefox processes

Some issues, especially those related to Firefox not starting properly, can be caused by an existing Firefox process, such as when Firefox hangs or is not responding - How to fix. When Firefox won't start, an error says it's already running, or you suspect that files could be locked, checking for running processes is a good idea.

  1. Check the process list to see if Firefox is running, and if so how many instances are running. The procedure and name of the binary vary by operating system.
    • Windows (firefox.exe): Open Task Manager by pressing Ctrl+Shift+Esc, switch to the Processes tab, look through the entire list for all firefox.exe processes.
    • Mac (firefox-bin): Open Activity Monitor from Macintosh HD/Applications/Utilities. Look through the entire list for all firefox-bin process names.
    • Linux (firefox or firefox-bin): With most Gnome-based distributions, Select System->Administration->System Monitor. Select the Processes tab, and look for all firefox-bin and/or firefox processes.
  2. You may need to end processes, especially if there is more than one Firefox process or if Firefox is not starting.
    • Windows: Click on the process name to kill, then click End Process
    • Mac: Click on the process name to kill, then click Quit Process
    • Linux: Right-click on the process name to kill, then choose Kill Process
  • If a problem is being caused by Firefox hanging, killing all Firefox processes may be necessary after every restart. In these cases, it is necessary to restart Firefox twice after killing all processes to verify that a problem is fixed.

Use WinDbg to debug crashes or hangs on Windows

WinDbg is a free Microsoft application used to debug programs. Mozilla supplies debugging symbols so that WinDbg can be used to debug Firefox releases on Windows. This is especially useful for cases in which the Mozilla Crash Reporter does not trigger or where spyware is causing the hang/crash.

After you get data from WinDbg, ask another helper to review it if you aren't yet familiar with reviewing crash reports.:

  1. Download WinDbg from
  2. Open WinDbg (Start Menu->All Programs->Debugging Tools for Windows->WinDbg)
  3. From the File menu, choose Open Executable
  4. Important: Ensure "Debug child processes" is selected
  5. In the Open File window, browse to C:\Program Files\Mozilla Firefox and choose firefox.exe. Click Open.
  6. A large, white command box with some text in it will appear. At the bottom of this box is a text input box where you can enter commands. Enter these three commands, one at a time, in order: (Type them exactly, and include the period before each command)
  7. Wait up to 30 minutes for the last command to finish, it needs to download ~70MB of data
  8. When it has finished, open the Debug menu (at the top) and choose Go.
  9. When Firefox opens, try to make it crash as before. (If it is crashing on a specific website, go to that website)
  10. When it crashes, you will see an error in the windbg command box.
  11. After it has crashed, enter this command in the text box at the bottom of the command box: (include the exclamation point before the command)
    • !analyze -v -f
  12. Copy and paste the entire text in the command box into a new forum post.

Good things to know

When providing support for users, there are many things that are useful to know.

Where to get help

To learn about resources available to support volunteers, read the Live Chat basic support handbook.

  • Search the knowledge base - most questions can be fully answered with a quick KB search.
  • Contributors chat: #sumo on irc or Contributors on Spark
  • If you have suggestions or feedback about support, or if you think you have encountered a new issue, you can post in the Contributors forum.

Finding the profile folder

  • Instructions for finding the profile folder are provided in the knowledge base. For instructions on a different operating system, simply choose another operating system at the right of the page.

Where Firefox stores data

When troubleshooting, it is often important to know where Firefox's data is stored. It is important that we never cause unintended data loss - this includes cookies! All of these files are stored in the Firefox profile folder.

  • places.sqlite: Bookmarks and history, this can become corrupt in some cases.
  • cookies.sqlite: All saved cookies, this can become corrupt in some cases.
  • prefs.js: This file stores all user preferences, including: the home page, installed add-ons, activated theme, cookie behavior, Clear all history options, extension settings, and printer settings. If this file is corrupt, it can be reset to restore all preferences to their defaults. The best way to reset this file is to check "Reset all user preferences to Firefox defaults" in the Safe Mode window.
  • mimetypes.rdf: All file-type associations as configured in Options/Preferences...Applications. This file can be safely removed if corrupt.
  • extensions.ini, extensions.rdf, extensions.cache: Temporary files for installed extensions. These may become corrupt and need to be deleted
  • signons.sqlite and key3.db: These files store saved passwords and exceptions. Both the signons file and the key file must be copied to back these up.
  • cert8.db: Saved security certificates. If this file is unreadable or corrupt, the Fix the "Could not initialize the application's security component" error message error may result.

Differences between operating systems

Live Chat gets users who need help on all three operating systems that Firefox supports. Supporting multiple operating systems is not hard, as long as you are familiar with a few key differences between operating systems.

Windows Mac Linux
Options accessed from Tools or Firefox...Options Preferences accessed from Firefox...Preferences Preferences accessed from Edit...Preferences
Firefox usually installed in C:\Program Files\Mozilla Firefox Firefox installed in /Applications folder. Installation path varies; most distributions don't use one
Menu bar on each window The global menu bar at the top of the screen is used for all applications. Menu bar on each window
Files on the hard drive accessed with Windows Explorer, launched by opening My Computer Files on the hard drive accessed with Finder, launched by clicking Macintosh HD Files accessed through Nautilus or Konqueror, usually from the desktop{PATH}
Right click used to access context menus On Macs without a right mouse button, Command+Click used to access context menus Right click used to access context menus
To quit Firefox, close all Firefox windows or use File or Firefox...Exit Closing all Firefox windows will not quit the application. File...Quit must be used To quit Firefox, close all Firefox windows or use File...Exit
Running processes available through Task Manager, Ctrl+Shift+Esc Running processes available through Activity Monitor, available in /Applications Running processes available by running ps -e in a Terminal window
PDF files work with Adobe Reader plugin There is no PDF plugin available, users must download the file and open with Adobe Reader or Preview PDF files work with Adobe Reader plugin or open source PDF viewers installed in Linux
Firefox 4 supports Windows 2000, XP, and higher Firefox 4 supports Mac OS 10.5 (Tiger) and higher Firefox 4 requires GTK2.10 or higher (RHEL/Centos 4.7+ or 5.0+)

Using about:config

about:config is an interface for editing advanced Firefox preferences, which is often necessary to fix problems when they are set wrong.

  • The screencast below shows how to use about:config to fix User Agent problems.

How to take screenshots on all three operating systems

Obtaining a screenshot is helpful when you aren't sure what a user's problem is. A screenshot can allow you to quickly see what a user is referring to.

  • Windows:
    1. Press the Print Screen button on the keyboard
    2. Open an image editor such as Microsoft Paint. (Microsoft Paint can be found in the Start Menu under All Programs->Accessories)
    3. From the Edit menu, select Paste
    4. Save the resulting image as a PNG file, then upload it to the forum.
  • Mac:
    1. Press Command+Shift+3 to save a screenshot in PNG format on the desktop. (Mac OS 10.4+)
    2. Upload the file from the Desktop to the forum
  • Linux:
    1. Press the Print Screen button to save a screenshot in PNG format.
    2. Upload the file from the Desktop to the forum

Know how to use features that commonly confuse users

As helpers, we need to be exceptionally familiar with areas of Firefox that users get stuck on. Many helpers do not use all of Firefox's features themselves, so a quick refresh of some of the basics is important.

  • Bookmarks and the Smart Location Bar (Awesomebar): To learn more, read Bookmarks in Firefox. For an overview, watch Mike Beltzner's screencast.
  • Startup preferences and tab restore: If these settings are changed in Options/Preferences, Firefox may not offer to restore tabs when closing Firefox.
  • Download locations: The default download location is configured in Options/Preferences in the General options panel. On Windows Vista, this has changed to the Downloads folder instead of the Desktop by default, confusing users used to Windows XP.
  • Application management: File type associations are configured with the Applications panel in Options/Preferences. This includes whether to save files, open with a specific application, ask the user each time, or use a plugin.
  • Disabling plugins: Plugins can be disabled without restarting Firefox using Tools or Firefox->Add-Ons->Plugins. If a plugin is misbehaving, disabling and re-enabling can often resolve it.

Removing files from the profile folder

If files in the profile folder are corrupt, it is often necessary to remove them. To avoid data loss, always rename files and folders instead of deleting.:

  • For preferences (prefs.js), bookmarks/history (places.sqlite), or window/toolbar settings (localstore.rdf), use the Safe Mode window to reset the file.
  • For other files, or if the safe mode steps didn't work, manually rename the file:
    1. Open the Profile Folder. See Differences between operating systems above for specific instructions.
    2. Make sure Firefox is closed. If a chat window is open in Firefox, the user should return to live chat using another browser.
    3. Right click (Mac: Command+click) on the file to remove, and select Rename.
    4. Type a new name for the file. A common practice is to simply add .old or .bak to the end of the filename.
    5. Restart Firefox to allow the file to be regenerated

How to know when a problem is not caused by Firefox

Many questions users ask are actually related to other programs or the operating system. It is important to be as polite as possible and verify information before informing the user that another program is at fault.

  • Have the user try in another browser. If the same symptoms happen in both browsers, the problem is most likely not Firefox. Check firewall software, spyware, and network connections.
  • Check to see whether malware is could be causing the problem. See Troubleshoot Firefox issues caused by malware

Common helper mistakes

We periodically collect information on common errors and mistakes made by live chat helpers, so that everyone knows to avoid them in the future. This are a few of the most common mistakes that we should all try to avoid.

  1. Jumping straight to a solution
    • Helpers will often read a question and jump straight toward offering a solution. For example, a user with a problem logging in might be told immediately to try Firefox safe mode. Instead of doing this, the helper should have first verified details.
  2. Not asking enough questions
    • Remember to always verify everything and ask questions to narrow down the problem. If you aren't sure that a user has tried something, ask questions to make sure.
  3. Providing a general solution
  4. Not asking for help
    • The best helpers are the ones who ask for the most help. No one knows the answer to all questions, and everyone is expected to ask in the Contributors chatroom when troubleshooting is involved in Live Chat.
  5. Not respecting users' data
    • While cookies or saved passwords might not be important to everyone, we must treat all data as important unless the user specifies otherwise. This means that bookmarks should never be deleted, cookies should never be cleared, and browsing history should not be erased without the user being informed of data loss.
    • In cases where data files must be removed for troubleshooting, always rename rather than delete. In cases where bookmarks are restored, always make a backup.
    • When uninstalling Firefox, verify that the user does not check the box to erase the profile.
    • When using Profile Manager, make sure that the old profile is not deleted.
    • When there are problems on one website, remove cookies for that one website rather than clearing all cookies.
  6. Responding inappropriately to abusive users
    • If a user in live chat wants to talk about something besides Firefox, politely explain that the chat service is for Firefox Support only. Never assume that a user is a "troll." If a user continually violates the rules, you may end the chat.
    • Avoid:
      • Arguing with users. If the user doesn't have a question or refuses to follow advice, either transfer the chat to a room monitor or send the user to the forum.
      • Profanity, playing along with, or encouraging abusive users (inform abusive users about the rules, and close the chat if they refuse to comply).
      • Calling users a troll. We never assume that someone is a "troll". Many users are genuinely confused, so being patient with users is required. If you are not sure, invite a room monitor. Always assume good faith.
  7. Not having fun
    • Support volunteers represent the broader Mozilla volunteer community to Firefox users. Helping support users lets you meet Mozilla community members, learn about Firefox, and interact directly with the community. While we are concerned with making users happy, an equally important aspect of a support community is interaction amongst its members. So take the opportunity to get to know people - both those involved with support as well as those from elsewhere around Mozilla.
These fine people helped write this article: zzxc, scoobidiver. You can help too - find out how.

Last Update: 2011-03-19

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