How can I clear duplicate browser entries from the Open With list in Windows?

Why does my right-click menu show broken Firefox icons and how do I fix it?

Understanding the “Open With” Menu Glitch

Windows 10 and 11 users often report a cluttered “Open With” context menu containing multiple Mozilla Firefox entries. You notice this immediately when right-clicking a PDF or HTML file. Instead of a single, functional Firefox icon, you see a list containing duplicate entries. Many of these display a generic “unknown file” icon rather than the official browser logo.

If you click these generic icons, Windows prompts you to select an app manually because the link points to a location that no longer exists. This indicates that your operating system retains outdated pointers to deleted or moved software files.

The Technical Cause: Orphaned Registry Keys

This clutter stems from how Windows manages file associations. When you install Firefox, the browser registers itself to handle specific file types like URLs, PDFs, and HTML documents.

The issue arises during removal or migration. If you uninstall an older version, switch between editions (such as moving from Stable to Nightly), or delete a specific user profile, the uninstaller may fail to clean these registration keys. Consequently, Windows believes the software is still installed.

This is particularly common with “Portable” editions of Firefox. If you move a portable installation folder from one drive (e.g., E:\) to another (e.g., F:\), the registry keys pointing to the old drive remain active. Windows does not automatically scan for these broken paths, resulting in “ghost” entries in your context menu.

Solution: Cleaning the Windows Registry

To resolve this, you must manually excise the invalid keys using the Windows Registry Editor. This process is precise and effective.

Warning: The Registry contains sensitive system configuration data. Create a backup or System Restore point before deleting keys.

Step 1: Launch the Registry Editor

1. Press the Windows + R on your keyboard to open the Run dialog.
2. Type regedit and press Enter.
3. If prompted by User Account Control, click Yes to grant permission.

Step 2: Locate the Firefox Associations

Navigate to the root class definitions by double-clicking HKEY_CLASSES_ROOT in the left pane. You are looking for keys that begin with specific identifiers. You can type “Firefox” to jump to them quickly.

Focus on locating keys with these prefixes:

• FirefoxHTML (followed by unique characters)
• FirefoxPDF
• FirefoxURL

You will likely see multiple variations, such as FirefoxHTML-308046B0AF4A39CB. Each key represents a specific installation record.

Step 3: Verify and Delete Invalid Keys

You must distinguish between the “live” key (your current browser) and the “dead” keys (the duplicates).

1. Inspect the Path: Double-click a FirefoxHTML (or PDF/URL) key to expand it.
2. Check the Icon: Click on the sub-key named DefaultIcon.
3. Read the Data: Look at the “Data” column in the right pane. It displays the file path, for example: C:\Program Files\Mozilla Firefox\firefox.exe,1.
4. Verify: Check if that path actually exists on your computer.
   • If the path is incorrect (e.g., points to an old drive letter or deleted folder): This is a corrupted entry. Right-click the parent key (e.g., FirefoxHTML-xyz) and select Delete.
   • If the path is correct: Do not touch it; this is your active browser.

Repeat this verification process for all FirefoxHTML, FirefoxPDF, and FirefoxURL entries. Once you delete the obsolete keys, the changes take effect immediately. The next time you right-click a file, the “Open With” menu will display only the valid, active Firefox entry.