Why Can't Mac Download Firefox

Please select a browser below to access instructions for configuring your browser to use the certificates on your CAC.

IE and Chrome

Installing Adobe Acrobat Reader DC is a two-step process. First you download the installation package, and then you install Acrobat Reader DC from that package file. Click Download Firefox. Note: If you want to have a choice of the language for your Firefox installation, click the Download options and other languages link instead. Once the download has completed, the file (Firefox.dmg) may open by itself and pop open a Finder window containing the Firefox application.

First check whether your certificates are already available to your browser.

For Internet Explorer 8.0 and above:

  1. Navigate to Tools > Internet Options > Content and click Certificates.
  2. On the Personal tab, review the list of certificates to determine if your CAC certificates are in the list. The certificates on your CAC will be issued by a DoD CA.
  3. If the certificates appear in the list, you are finished. If the certificates do not appear in the list, please see the note below.
  1. Method 1 Using Firefox Add-on. One of the easy ways to download video on Firefox is using the Firefox add-on. If you search 'Firefox YouTube Add-on' online, you can easily find this site.
  2. Download Firefox: Private, Safe Browser and enjoy it on your iPhone, iPad, and iPod touch. ‎You have the right to own your life – and your data. That’s why Firefox fights for you with tech you can trust.

For Google Chrome:

  1. Navigate to Tools > Options > Under the Hood and click Manage Certificates in the HTTPS/SSL section.
  2. On the Personal tab, review the list of certificates to determine if your CAC certificates are in the list. The certificates on your CAC will be issued by a DoD CA.
  3. If the certificates appear in the list, you are finished. If the certificates do not appear in the list, please see the note below.

NOTE: If your certificates are not in the list and you’re using ActivClient, please make sure it is installed correctly. If your certificates are not in the list and you are using other middleware, you can contact your CC/S/A for more information on the middleware requirements for your organization. You can find their contact information on our Contact Us tab.


Below are complete instructions for using Firefox with your CAC. You may also download these instructions.

Install Certificates from InstallRoot

  1. Download and install the InstallRoot tool following the instructions in the InstallRoot User Guide or watch this video to learn how:
  2. Open the InstallRoot tool and select Firefox/Mozilla/Netscape from the Select Trust Store picklist at the bottom of the window.
  3. Ensure only the top Install DoD NIPRNET Certificates box is checked.
  4. Click the Install button and wait for the installation to complete. Please wait until you see a confirmation dialog indicating the tool is finished.
  5. Using Common Access Card (CAC) certificates in Firefox

    These instructions will enable ActivIdentity’s ActivClient software to work within Firefox. Before proceeding, try to ensure the latest version of ActivClient is installed by going to the ActivClient website to check the latest version. Before installing the latest version, please uninstall any previous versions of ActivClient.

    As of version 6.2, ActivClient by default configures Firefox to accept the CAC certificates without any additional configuration. You may use the following instructions to verify that it has been installed properly. If using an older version of ActivClient, these instructions will assist with proper configuration.

    1. Open Firefox
    2. Click on Tools > Options in the menu bar.
    3. In the Options window, go to Advanced > Encryption > Security Devices.
    4. In the new window, click on Load.
    5. Enter “ActivClient(CAC)” for the Module Name.

      Click Browse to the right of the Module Filename field. Browse to the location of the ActivClient PKCS11 library, acpkcs211.dll. This is typically located at C:Program Files (x86)ActivIdentityActivClientacpkcs211.dll in ActivClient 6.2, and C:Windowssystem32acpkcs201-ns.dll in ActivClient 6.1 and earlier.

      Click OK, and then OK again in the confirmation window.

    6. The confirmation message will show that the security device (CAC) was loaded. CAC certificates can now be used with the browser. Click OK to close the window.
    7. Ensure the Online Certificate Status Protocol (OCSP) is Performing Revocation Checking

      With any versions of ActivClient later than 6.2, these settings will be automatically configured. However, these instructions can be used to confirm proper configuration for older versions of ActivClient.

      1. Open Firefox
      2. Click on Tools > Options in the menu bar.
      3. In the Options window, go to Advanced > Encryption > Validation.
      4. Ensure the option Use the OCSP to confirm the current validity of certificates is checked. Also ensure When an OCSP server connection fails, treat the certificate as invalid is checked.


To get started you will need:

  • CAC (see note below)
  • Card reader

You can get started using your CAC on your Mac OS X system by following these basic steps:

  1. Get a card reader
    Typically Macs do not come with card readers and therefore an external card reader is necessary. At this time, the best advice for obtaining a card reader is through working with your home component. In addition, please review the DoD CAC Reader Specifications for more information regarding card reader requirements.
  2. Download and install the OS X Smartcard Services package
    The OS X Smartcard Services Package allows a Mac to read and communicate with a smart card. In order for your machine to recognize your CAC certificates and DoD websites as trusted, the installer will load the DoD CA certificates on OS X. Please refer to this page for specific installation instructions.
  3. Address the cross-certificate chaining Issue
    These instructions walk through adjusting the trust settings on the Interoperability Root CA (IRCA) > DoD Root CA 2 and the US DoD CCEB IRCA 1 > DoD Root CA 2 certificates to prevent cross-certificate chaining issues. This can make it appear that your certificates are issued by roots other than the DoD Root CA 2 and can prevent access to DoD websites.
  4. Configure Chrome and Safari, if necessary
    Safari and Google Chrome rely on Keychain Access properly recognizing your CAC certificates.
    1. In Finder, navigate to Go > Utilities and launch KeychainAccess.app
    2. Verify that your CAC certificates are recognized and displayed in Keychain Access

Note: CACs are currently made of different kinds of card stock. To determine what card stock you have, look at the back of your CAC above the magnetic strip. Most CACs are supported by the Smartcard Services package, however Oberthur ID One 128 v5.5 CACs are not. Third party middleware is available that will support these CACS; two such options are Thursby Software’s PKard and Centrify’s Express for Smart Card. /smartboard-download-108-for-mac/.

This article describes steps to take if you are unable to download or save files using Firefox.

Known issue: Users experiencing failing downloads after an update to Firefox 69.0.2 or Beta 70.0b11+ should first refer to the following article Unable to download files in Windows 10 when Parental Controls are on.
Note: The Refresh Firefox feature can fix many issues by restoring Firefox to its default state while saving your essential information. Consider using it before going through a lengthy troubleshooting process.

Table of Contents

  • 7Change file type settings
  • 9Enable downloads blocked by Security Zone Policy

Firefox includes a download protection feature to protect you from malicious or potentially harmful file downloads. If Firefox has blocked an unsafe download, you will see a warning message about the file in the Downloads panel, along with options for handling the pending download. You can open the Downloads panel to view completed and pending downloads by clicking on the Downloads button (the down arrow on your toolbar). See the articles Where to find and manage downloaded files in Firefox and How does built-in Phishing and Malware Protection work? for more information.

Clearing the download history can fix some problems with downloading files:

  1. Click the Downloads button , and then click Show all downloads. The Downloads window will open.
  2. In the Downloads window, click .
  3. Close the Downloads window.

Firefox may not be able to download files if there is a problem with the folder in which downloaded files are saved:

  1. Click the menu button and select ..
  2. Select the General panel.
  3. Go to the Downloads sectionFind the Downloads section under Files and Applications.
  4. Click the button next to the Save files to entry.
  5. Choose a different download folder for saving files.
  6. Close the about:preferences page. Any changes you've made will automatically be saved.

If you have tried the above suggestions, you can restore the default Firefox download folder settings:

  1. Type about:config in the address bar and press EnterReturn.
    A warning page may appear. Click to continue to the about:config page.
  2. In the Search field, enter browser.download.
  3. If any of the following settings have a status of modifiedare in bold text, reset their values. To reset a value, right-clickhold down the Ctrl key while you click the setting and select Reset from the context menuclick the Delete or Reset button, depending on the preference:
    • browser.download.dir
    • browser.download.downloadDir
    • browser.download.folderList
    • browser.download.lastDir
    • browser.download.useDownloadDir
  4. If desired, you can revert back to your preferred download folder settings in your Firefox OptionsPreferencesGeneral panel, in the Downloads section under Files and Applications.

If you receive the error <filename> could not be saved, because an unknown error occurred. , your problem might be caused by an interaction with the Safari browser and your operating system.

To fix the problem, open Safari's Preferences and change the Save downloaded files to: setting to a valid folder (such as your Desktop). Then restart Firefox.

If you receive the error <filename> could not be saved, because you cannot change the contents of that folder. Change the folder properties and try again, or try saving in a different location., your problem might be caused by corrupt plist files.

To fix this problem, go to your home directory and delete this preference file:

Why Can't I Install Firefox

  • ~/Library/Preferences/com.apple.internetconfig.plist

If downloading certain file types does not work, check to make sure Firefox is not set to handle those file types differently from others. See Change what Firefox does when you click on or download a file for instructions on how to view and change how different file types are handled.

Reset download actions for all file types

To reset how all file types are handled by Firefox back to default:

  1. Open your profile folder:

    • Click the menu button , click Help and select Troubleshooting Information.From the Help menu, select Troubleshooting Information. The Troubleshooting Information tab will open.
    • Under the Application Basics section next to Profile FolderDirectory, click . A window will open that contains your profile folder.Your profile folder will open.
    Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
  2. Click the Firefox menu and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu and select Quit.
  3. Delete or rename the mimeTypes.rdf file (for example, rename it mimeTypes.rdf.oldhandlers.json file (for example, rename it handlers.json.old ).
  4. Restart Firefox.

Internet security software, including firewalls, antivirus programs, anti-spyware programs, and others can block certain file downloads. Check the settings in your security software to see if there is an setting that may be blocking downloads.

To diagnose whether Internet security software is causing problems, you can try temporarily disabling it, seeing if downloads work, and then re-enabling the software.

Downloading an executable file (e.g., an .exe or .msi file) may fail, with the Downloads window showing Canceled under the file name.

This happens because Firefox honors your Windows security settings for downloading applications and other potentially unsafe files from the Internet. To resolve this problem, use the solution given below.

Reset system Internet Security settings

You can reset your system Internet security settings in Internet Explorer. See How to reset Internet Explorer settings at Microsoft Support for instructions.

Mozilla Firefox Download

You may be able to diagnose your download problem by following the steps given in the Troubleshoot and diagnose Firefox problems article.

How To Download Firefox In S Mode

Based on information from Unable to save or download files (mozillaZine KB)