Mozilla Firefox can’t load websites but other browsers can

Internet Security software blocking Firefox in Maine

If you were able to load websites until you updated Firefox or until your Internet security software was updated, reconfigured or a new one was added, your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is likely preventing Firefox from connecting to the Internet.

In general, you should make sure your Internet security software is up-to-date and remove Firefox from your program’s list of trusted or recognized programs, then add it back.

Firefox connection settings

If you connect to the Internet through a proxy server that is having connection problems, you will not be able to load websites. To check your connection settings in Firefox:

  1. Click the menu button and choose Options.
  2. In the General panel, go down to the Network Proxy
  3. In the Network Proxy section, click Settings….
  4. Change your proxy settings:
    • If you don’t connect to the Internet through a proxy (or don’t know whether you connect through a proxy), select No Proxy.
    • If you connect to the Internet through a proxy, compare Firefox’s settings to another browser’s (such as Internet Explorer — see Microsoft’s guide to proxy settings).
  5. Close the Connection Settings dialog.
  6. Close the about: preferences Any changes you’ve made will automatically be saved.

If you find that changes you make to your Firefox connection settings are not remembered when you restart Firefox.

Mozilla Firefox can’t load websites 


Firefox supports IPv6 by default, which may cause connection problems on certain systems. To disable IPv6 in Firefox:

  1. In the address bar, type about: config and press Enter.
    • The about: config “This might void your warranty!”warning page may appear. Click I accept the risk! To continue to the about: config page.
  2. In the Searchfield, enter dns.disableIPv6.
  3. In the list of preferences, double-click dns. disable IPv6 to set its value to true.

DNS Prefetching

Firefox attempts to speed up loading new websites by using DNS Prefetching, which can cause page load errors with some system configurations. To disable DNS Prefetching:

  1. In the address bar, type about: config and press Enter.
    • The about: config “This might void your warranty!”warning page may appear. Click I accept the risk! To continue to the about: config page.
  2. Right-click in the list of preferences, select New, and then select Boolean.
  3. In the Enter the preference name field, enter dns.disablePrefetch and click OK.
  4. Select true when prompted to set the value and click OK.

Firefox cannot load certain websites

If you find that Firefox can load some websites but not others, first clear your Firefox cookies and cache:

  1. Click the Library button , click History and select Clear Recent History….
  2. In the Time Range to clear:drop-down, select everything.
  3. Click the arrow next to Detailsto display the list of items that can be cleared.
  4. Select both Cookiesand Cache.
  5. Click Clear Now.

Check for malware

If clearing your cookies and cache did not enable you to load the websites that did not work in Firefox, you should check your computer for malware. Certain types of malware are known to target Firefox and can prevent it from loading various websites:

  • If you have an antivirus or Internet security program, update its detections database and do a full scan of your system.
  • If you still have problems, follow the instructions in Troubleshoot Firefox issues caused by malware.

Firefox uses too much memory on Windows 10 (RAM) – How to Fix

Mozilla Firefox uses too much memory (RAM) problem | Michigan:

Firefox is one of the most popular web browsers on the market. However, Mozilla Firefox has its issues and many users report that Firefox uses too much memory on their Windows 10 PC. This can be a major problem, so today we’re going to show you how to fix it.

Solution 1 – Update Firefox to the latest version

If you’re having memory issues in Firefox, be sure to check if you’re using the latest version. Sometimes, certain versions can have performance issues so it’s important that you download and install the latest version of Firefox. Checking for updates in Firefox is rather simple and you can do it by following these steps:

  1. Click the Menu button in the top right corner and click the question mark icon at the bottom. 
  2. Click about Firefox from the menu.
  3. A new window will now appear. Check if Firefox is up to date. If your version is outdated, Firefox will download the latest version automatically. 

After updating Firefox to the latest version, check if memory issues still persist.

Solution 2 – Start Firefox in Safe Mode

Memory usage problems in Firefox can occur due to third-party extensions and in order to fix the problem, it’s advised you start Firefox in Safe Mode. In Safe Mode, Firefox uses default settings and extensions, allowing you to easily troubleshoot any problems. To start Firefox in Safe Mode, do the following:

    1. Click the Menu icon in the top right corner. Now, click on question mark icon and choose Restart with Add-ons Disabled
    2. When the confirmation message appears, click on Start in Safe Mode.

You can also start Firefox in Safe Mode with a useful keyboard shortcut. To do so, be sure to close Firefox completely first. After that, you can start Firefox by doing the following:

      • Locate Firefox shortcut on your desktop.
      • Press and hold the Shift key on your keyboard and double-click the Firefox shortcut.
      • If the confirmation message appears, choose the option to start Firefox in Safe Mode.

After starting Firefox in Safe Mode, check if the problem still persists. If memory problems are gone, it means that your configuration or a third-party extension is causing problems with Firefox.

Firefox uses too much memory (RAM)

Solution 3 – Switch to the default theme

Many users like to customize Firefox with new themes. Although some themes look visually impressive, they can use too much of your memory. To fix this problem, it’s advised you switch back to the default theme and check if your memory usage changes. To do that, follow these steps:

1. Click the Menu button in the top right corner. Choose Add-ons from the menu.

2. Go to the Appearance tab and make sure that Default theme is selected.

After selecting the Default theme, restart Firefox and check if everything is working properly.

Solution 4 – Disable all extensions

If you don’t use custom Firefox themes, you might want to disable third-party extensions. Extensions can often cause increased memory usage and in order to fix it, we advise you to disable all extensions. To do that, follow these simple steps:

  1. Click the Menu button in the top right corner and choose Add-ons from the menu.
  2. Navigate to the Extensions tab. A list of all installed extensions will appear. Click the Disable button next to an extension to disable it.
  3. After doing that, restart Firefox.
  4. After Firefox starts again, check if the problem still persists. If the issue is resolved, you need to go back to the Extensions tab and enable extensions one by one. Be sure to restart Firefox after enabling each extension.
  5. After finding the problematic extension, disable or remove it, or download the latest version.

Users had issues with GhosterySkype Click to CallGreasemonkey and dictionary extensions. If you’re using these extensions, we advise you to disable them and check if that solves the issue.

Solution 5 – Disable specific plugins

In addition to extensions, certain plugins can cause memory issues with Firefox. To fix the problem, you might want to try disabling certain plugins. To do that, follow these steps:

  1. Click the Menu button and choose Add-ons.
  2. Go to the Plugins tab and select Never Activate for a specific plugin. Restart Firefox.
  3. After Firefox restarts, check if the issue still persists. If the problem isn’t resolved, try disabling a different plug-in. After finding the plug-in causing memory issues, be sure to enable all other plug-ins except that one.
  4. If you need to use that specific plug-in, be sure to update it to the latest version and check if that solves the problem.

    Solution 6 – Hide intrusive content

    Certain web content can be quite demanding on your resources and in order to prevent high memory usage you might have to hide that content. According to users, Flash content and certain scripts can be quite demanding in terms of resources so you’ll have to disable them. To do that, you’ll need to use third-party extensions. To block Flash content, you can use the Flashblock extension. As for scripts, the NoScript extension will allow you to choose the scripts to disable on specific websites. After disabling certain scripts and Flash content memory usage, Firefox should improve. Keep in mind that disabling certain scripts can affect how some websites work, so choose carefully which scripts you disable.

    Solution 7 – Check for Flash hardware acceleration

    High memory usage in Firefox can occur due to Flash hardware acceleration, but you can easily fix that. To do that, you need to follow these steps:

    1. Open a page that has Flash video.
    2. Right-click the video player and choose Settings from the menu.
    3. Click the icon at the bottom left to open Display panel.
    4. Now, check Enable hardware acceleration.

    After doing that, be sure to check if the issue is resolved.

    Solution 8 – Restart Firefox

    You can temporarily fix this problem by restarting Firefox. Some users reported that Firefox memory usage can increase if the application is running for prolonged periods of time, so be sure to try this solution. While this is a temporary workaround, it should work for most users.

    Solution 9 – Close unnecessary tabs

    Each open tab increases the amount of memory Firefox uses. If you tend to have more than ten tabs open at all times, you might experience certain memory issues. In order to improve performance and fix this problem, we strongly advise you close unnecessary tabs and keep only the ones you need open.

    Solution 10 – Close other applications

    Open tabs in Firefox will increase your memory usage, but other applications can also contribute to this problem. Some applications can be quite demanding on your resources and that can leave less memory available to Firefox. If you’re having any memory issues with Firefox, we recommend that you close any demanding applications running in the background. By doing that, you’ll free your memory and improve Firefox performance.

    Solution 11 – Use about:memory feature

    Firefox allows you to examine your memory usage with ease. This process is rather simple and you can do it by following these steps:

    1. In the Firefox address bar, enter about:memory and navigate to that page.
    2. On this page, you can view detailed reports regarding memory usage. You can also free your memory with ease. To do that, click Minimize memory usage button in the free memory section.
    3. Several users reported that you can also solve this problem by using the RAMBack extension, so be sure to try that as well.

      Solution 12 – Change Firefox settings

      According to users, you might be able to reduce Firefox memory usage simply by changing Firefox settings. To do that, follow these steps:

        • A list of options will appear. Find these specific options and change their values like so:
          1. browser.cache.memory.capacity to 0
          2. browser.cache.memory.enable to false
          3. browser.sessionhistory.max_total_viewers to 0
          4. browser.tabs.animate to disable
          5. browser.sessionstore.max_concurrent_tabs to 0
        • After making the changes, restart Firefox and check if the problem is resolved.In the Firefox address bar, enter about:config. If you get a warning message, choose the proceed option.