How to Fix Crashes for Mozilla Firefox

Introduction

We all rely on our web browsers to get us through the day, so serious problems with your browser of choice can have a serious impact on your productivity, peace of mind, or even less important things like Netflix binge watches. This guide will take you through troubleshooting steps to get Mozilla Firefox working properly on your machine.
Mozilla Firefox browser.

? What kind of problem are you having with Firefox?

  1. Firefox opens, but crashes when browsing
  2. Firefox will not open at all

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We all rely on our web browsers to get us through the day, so serious problems with your browser of choice can have a serious impact on your productivity, peace of mind, or even less important things like Netflix binge watches. This guide will take you through troubleshooting steps to get Mozilla Firefox working properly on your machine.
Mozilla Firefox browser.

There are 2 main Operating Systems for personal computers currently available, Windows and macOS.

Windows
Windows runs on computers produced by multiple companies, such as Lenovo, Asus, Dell, Toshiba, Hewlett Packard, Acer, and Sony.Windows 10
macOS
Apple is the only company that makes macOS computers.macOS Mojave
Before you restart or shut down your PC, make sure to save all necessary work to prevent data loss.
  1. Select the Start menu, then select Power.
    Windows 10 Start Menu
    Windows 10 Power Button
  2. Select Restart.
    Windows 10 Power menu with Restart highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
  1. Open Mozilla Firefox.
    Mozilla Firefox.
  2. Select the Menu button located in the top right corner of the window.
    Menu.
  3. Select Library.
    Firefox Menu with Library highlighted.
  4. Select History.
    Library with History highlighted.
  5. Select Clear Recent History.
    History with Clear Recent History highlighted.
  6. For Time range to clear, select Everything. Then select Clear Now.
    Clear history with Time range and Clear Now button highlighted.

Firefox does not run in the background normally.

  1. Select the X in the top-right corner of the window to close Firefox.
    Firefox with close X highlighted.
  2. Make sure the Firefox icon does not appear on the Taskbar.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

Extensions provide extra features to Firefox. Sometimes, these Extensions are not coded well, break after a Firefox update, or because they change the way Firefox works in a malicious way to show you advertisements.

Disabling or removing unneeded or unwanted Extensions can help resolve these problems.

It is recommended to delete all unwanted Extensions, then disable all other Extensions, then test the browser, then enable your wanted extensions one by one, testing each time to find the extension that's causing problems.

  1. Open Mozilla Firefox.
    Mozilla Firefox.
  2. Select the Menu button located in the top right corner of the window.
    Menu.
  3. Select Add-ons.
    Menu with Add-ons highlighted.
  4. Select Extensions on the left.
    Addons.
  5. Here you'll see a list of extensions installed.
    Firefox Extensions.

Disable An Extension

Disabling an Extension will leave it installed, but entirely deactivated making it do nothing, but easy to re-enable later should you need it. This is best if you're not entirely sure what the extension is for.

  1. Select the Disable button to turn the extension off.
    Extension with Disable button highlighted.
  2. The extension will show as (disabled).
    Extension disabled.

Remove An Extension

It is best to remove any Extensions you see that relate to advertising, or that you know you do not use.

  1. Select the Remove button for an Extension you don't want.
    Extension with Remove button highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

Our next step is to uninstall Mozilla Firefox.

In most cases, your bookmarks and saved passwords will be saved through uninstalling and reinstalling, but they can be lost during this process.

Any history, frequently used pages, cookies, and Extensions will be lost.

Any bookmarks, passwords, and extension settings could be lost if they are corrupt and causing the problems you are having.

  1. Select the Start menu, then select Settings.
    Start menu with Settings highlighted.
  2. Select Apps.
    Settings with Apps highlighted.
  3. In Apps & features, select Mozilla Firefox, then select Uninstall.
    Windows Apps and features with Uninstall highlighted.
  4. Select Uninstall for the conformation message.
    Uninstall conformation with Uninstall highlighted.
  5. The Helper will ask permission to run, select Yes.
    User Account Control prompt with Yes highlighted.
  6. The Uninstall Wizard will open, select Next.
    Firefox uninstall wizard welcome with Next highlighted.
  7. You'll be shown where Firefox is currently installed. Select Uninstall.
    Install location with Uninstall highlighted.
  8. Select Finish.
    Uninstall complete with Finish highlighted.
Before you restart or shut down your PC, make sure to save all necessary work to prevent data loss.
  1. Select the Start menu, then select Power.
    Windows 10 Start Menu
    Windows 10 Power Button
  2. Select Restart.
    Windows 10 Power menu with Restart highlighted.

We will use the built-in Edge browser on your computer to download and install Mozilla Firefox.

  1.  Open Microsoft Edge.
    Microsoft Edge.
  2. In the address bar at the top, type www.mozilla.com/firefox, then press enter.
    Edge address bar with address entered.
  3. Select Download now.
    Firefox download page with Download now highlighted.
  4. Select Run to start the installer right after downloading.
    Firefox download with Run highlighted.
  5. The installer will ask permission to run, select Yes.
    User Account Control with Yes highlighted.
  6. Select Install or Re-install (if you had Firefox installed before).
    Firefox installer with Re-install highlighted.
  7. The Import wizard should run, select Finish if prompted.
    Import wizard with Finish highlighted.
  8. Firefox should open automatically.
    Mozilla Firefox browser.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
If you are a PST, follow the Escalation Process to PTE.

By default, macOS does not quit programs when you close their windows. Quitting and restarting Firefox can often resolve these problems.

  1. Select Firefox on your Dock.
    Mozilla Firefox.
  2. Select the Firefox menu, then Quit Firefox.
    Firefox menu with Quit Firefox highlighted.
  1. From the menu bar across the top of the screen, select the Apple menu, then Restart...
    macOS Mojave Apple Menu with Restart highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
  1. Open Mozilla Firefox.
    Mozilla Firefox.
  2. Select the Menu button located in the top right corner of the window.
    Menu.
  3. Select Library.
    Firefox Menu with Library highlighted.
  4. Select History.
    Library with History highlighted.
  5. Select Clear Recent History.
    History with Clear Recent History highlighted.
  6. For Time range to clear, select Everything. Then select Clear Now.
    Clear history with Time range and Clear Now button highlighted.

By default, macOS does not quit programs when you close their windows. Quitting and restarting Firefox can often resolve these problems.

  1. Select Firefox on your Dock.
    Mozilla Firefox.
  2. Select the Firefox menu, then Quit Firefox.
    Firefox menu with Quit Firefox highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

Extensions provide extra features to Firefox. Sometimes, these Extensions are not coded well, break after a Firefox update, or because they change the way Firefox works in a malicious way to show you advertisements.

Disabling or removing unneeded or unwanted Extensions can help resolve these problems.

It is recommended to delete all unwanted Extensions, then disable all other Extensions, then test the browser, then enable your wanted extensions one by one, testing each time to find the extension that's causing problems.

  1. Open Mozilla Firefox.
    Mozilla Firefox.
  2. Select the Menu button located in the top right corner of the window.
    Menu.
  3. Select Add-ons.
    Menu with Add-ons highlighted.
  4. Select Extensions on the left.
    Addons.
  5. Here you'll see a list of extensions installed.
    Firefox Extensions.

Disable An Extension

Disabling an Extension will leave it installed, but entirely deactivated making it do nothing, but easy to re-enable later should you need it. This is best if you're not entirely sure what the extension is for.

  1. Select the Disable button to turn the extension off.
    Extension with Disable button highlighted.
  2. The extension will show as (disabled).
    Extension disabled.

Remove An Extension

It is best to remove any Extensions you see that relate to advertising, or that you know you do not use.

  1. Select the Remove button for an Extension you don't want.
    Extension with Remove button highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

Our next step is to uninstall Mozilla Firefox.

In most cases, your bookmarks and saved passwords will be saved through uninstalling and reinstalling, but they can be lost during this process.

Any history, frequently used pages, cookies, and Extensions will be lost.

Any bookmarks, passwords, and extension settings could be lost if they are corrupt and causing the problems you are having.

  1. Select Finder in your Dock.
    Finder.
  2. Select Go > Applications.
    Finder Go menu with Applications highlighted.
  3. Drag Firefox to the Trash icon on your Dock.
    Firefox being dragged to Trash.
  1. From the menu bar across the top of the screen, select the Apple menu, then Restart...
    macOS Mojave Apple Menu with Restart highlighted.

We will use the built-in Safari browser on your Mac to download and install Mozilla Firefox.

  1. Open Safari from your Dock.
    Apple Safari.
  2. In the address bar at the top, type https://www.mozilla.org/en-US/firefox/, then press return.
    Safari address bar with URL entered.
  3. Select Download now.
    Firefox download page with Download now highlighted.
  4. Select Firefox.dmg from Downloads.
    The exact file name will change as Firefox is updated with higher versions, but it will be similar.
    Safari Downloads with Firefox installer highlighted.
  5. Drag the Firefox App into your Applications folder.
    Firefox Disk Image showing Firefox App with arrow pointing to Applications shortcut.
  6. Once it has finished copying, eject the disk image for Firefox from your desktop by dragging it to Trash.
    Eject Firefox installer disk image.
  7. Open Firefox.
    Mozilla Firefox.
  8. You'll be asked for permission to run Firefox, select Open.
    Security dialog with Open highlighted.
  9. Firefox will open.
    Firefox browser window.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

There are 2 main Operating Systems for personal computers currently available, Windows and macOS.

Windows
Windows runs on computers produced by multiple companies, such as Lenovo, Asus, Dell, Toshiba, Hewlett Packard, Acer, and Sony.Windows 10
macOS
Apple is the only company that makes macOS computers.macOS Mojave

Sometimes Firefox can get stuck as it launches. Forcing it to quit and restarting it usually fixes this problem.

  1. On your keyboard, press the Control, Alt, and Delete keys at the same time.
    PC Desktop Keyboard with Ctrl-Alt-Del highlighted.
  2. Select Task Manager.
    Ctrl-Alt-Del screen with Task Manager highlighted.
  3. Select More details.
    Task manager with More details highlighted.
  4. Select any entries named Firefox or firefox.exe, then select End task.
    Task Manager with Firefox and End Task highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
Before you restart or shut down your PC, make sure to save all necessary work to prevent data loss.
  1. Select the Start menu, then select Power.
    Windows 10 Start Menu
    Windows 10 Power Button
  2. Select Restart.
    Windows 10 Power menu with Restart highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.

Sometimes Chrome can get stuck as it launches. Forcing it to quit and restarting it usually fixes this problem.

  1. Select the Apple menu, then Force Quit.
    Apple menu with Force Quit highlighted.
  2. Highlight Firefox in the list, and select Force Quit.
    Force Quit with Firefox and Force Quit highlighted.
  3. You'll be prompted if you're sure, select Force Quit.
    Force quit prompt with Force Quit button highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
  1. From the menu bar across the top of the screen, select the Apple menu, then Restart...
    macOS Mojave Apple Menu with Restart highlighted.
  1. Open your browser, and visit the website you had problems with at the start.
    Mozilla Firefox.
  2. Make sure the page loads properly, and try following a few of the links from the page.
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