Pop-up blocker settings, exceptions and troubleshooting

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  • Revision id: 302097
  • Created:
  • Creator: Flavius Floare
  • Comment: NEW Update KB - changed to third party redirects. To be published on 8/19. Edit title then, as well.
  • Reviewed: No
  • Ready for localization: No
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What are pop-ups?

Pop-up windows, or pop-ups, are windows that appear automatically without your permission. They vary in size, but usually don't cover the whole screen. Some pop-ups open on top of the current Firefox window, while others appear underneath Firefox (pop-unders).

Firefox allows you to control both pop-ups and pop-unders in Firefox Settings . Pop-up blocking is turned on by default, so you don't have to worry about enabling it to prevent pop-ups from appearing in Firefox.

When blocking a pop-up, Firefox displays an information bar (if it hasn’t been previously dismissed – see below), as well as an icon popup_icon_fx57 in the address bar.

PopupFx89Fx90Popup-mac

When you click either the OptionsPreferences button in the info bar or the icon in the address bar, a menu is displayed with the following choices:

  • Allow/Block pop-ups for <website address>
  • Manage pop-up settings…
  • Don't show this message when pop-ups are blocked
  • Show <pop-up web address>
Blocking pop-ups may interfere with some websites: Some websites, including some banking sites, use pop-ups for important features. Blocking all pop-ups disables such features. To allow specific websites to use pop-ups, while still blocking all others, you can add those specific websites to the list of allowed sites. Blocking pop-ups doesn't always work: Although Firefox blocks most pop-ups, some websites may show pop-ups using uncovered methods, even when they are blocked.

Additionally, to better protect you, Firefox also includes third-party redirect blocking, which stops websites from forcibly opening themselves as top pages outside of trusted browsing frames or windows, protecting you from content hijacking or clickjacking tactics

Both features work together to improve your browsing safety while keeping essential site functions intact.

Pop-up blocker settings

To access the pop-up blocker settings:

  1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button Fx89menuButton and select Settings.
  2. Select the Privacy & Security panel.
  3. Go down to the Permissions section.
    • Uncheck the box next to Block pop-up windows and third-party redirects to disable the pop-up blocker altogether.
    • Click the Exceptions… button to the right of Block pop-up windows and third-party redirects to open a dialog box to choose which sites are allowed to display pop-ups.
    Allowed Websites Pop-ups

The dialog box offers you the following choices:

  • Type or paste the address of a website and click the Allow button to add it to the list of sites that will be allowed to open pop-up windows.
  • Select a website from the list and click the Remove Website button to remove it from the exceptions list.
  • Click the Remove All Websites button to remove all websites from the exceptions list.

Click the Save Changes button to apply your changes.

Note: Allowing pop-ups for a trusted site also permits third-party redirect blocking; these settings are linked and must be toggled together. You can think of the third-party redirect blocking as an extension of the pop-up blocker, and it protects you by ensuring that pop-ups only open within a secure browser context.

Understand Firefox’s third-party redirect blocking

Third-party redirect blocking protects against deceptive websites that attempt to load their pages outside of approved browser environments, often overriding your tabs or opening content in full-screen or external windows.

This safeguard works alongside pop-up blocking, catching methods that bypass standard window behavior. When a site is permitted to use pop-ups, Firefox will still apply third-party redirect blocking rules to prevent malicious behavior.

Key protection benefits include:

  • Preventing content from breaking out of secure tabs
  • Avoiding hijacked full-screen prompts or fake login pages
  • Complementing the pop-up blocker by targeting evasive techniques

Pop-ups not being blocked

Is the pop-up coming from Firefox?

The pop-up may not actually be coming from Firefox. You can determine where the pop-up is coming from by the appearance of the window.

  • If you see the address bar with the Tracking Protection button Fx89ShieldIcon and the Site Identity button Fx89Padlock in the pop-up window, the pop-up is coming from Firefox.
  • If you don't see these buttons, you may have malware on your computer that causes the pop-ups. For help, see Troubleshoot Firefox issues caused by malware.

Is the pop-up blocker on and enabled for this site?

  1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button Fx89menuButton and select Settings.
  2. Select the Privacy & Security panel and go to the Permissions section.
  3. Make sure the Block pop-up windows checkbox is checked.
  4. To the right of Block pop-up windows, click the Exceptions… button. A dialog box will open with a list of sites that are allowed to show pop-ups.
  5. If the site that's opening pop-ups is listed here, select it and click Remove Website.
  6. Click on Save Changes to update your changes.
  7. Close the Settings page. Any changes you've made will automatically be saved.
Tip: Firefox’s third-party redirect blocking stays active whether or not a site is on the pop-up exceptions list. It adds a protective layer against forced third-party redirects or new window hijacking.

Is the pop-up shown after a mouse click or a key press?

Certain events, such as clicking or pressing a key, can spawn pop-ups regardless of if the pop-up blocker is on. This is intentional, so that Firefox doesn't block pop-ups that websites need to work.

Is it a true pop-up window?

Sometimes ads are designed to look like windows, but really aren't. Firefox's pop-up blocker can't stop these ads.

Mozilla surveys

When you visit a Mozilla website, sometimes you'll see a pop-up asking you to participate in a survey. The only third-party that Mozilla ever uses for surveys is Alchemer (formerly SurveyGizmo), which has been vetted by our legal and privacy teams. The Firefox pop-up blocker doesn't block these pop-ups.

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