How Chromium Handles Conflicting New Tab Extensions

This article explains how the Chromium web browser resolves conflicts when two or more installed extensions attempt to override the New Tab page simultaneously. It covers the browser's built-in priority rules, the role of user confirmation prompts, what happens when an active extension is disabled, and how users can manually choose which extension controls their New Tab experience.

The "Most Recently Enabled" Rule

In Chromium-based browsers, an extension uses the chrome_url_overrides API in its manifest file to replace the default New Tab page. However, the browser architecture only allows a single extension to control the New Tab page at any given time. It cannot merge them or display both.

When two extensions request control of the New Tab page, Chromium resolves the conflict using a "Last In, First Out" (LIFO) precedence rule. The extension that was most recently installed or enabled automatically wins the conflict and takes over the New Tab page. The older extension remains installed and active for other background tasks, but its New Tab override feature is suppressed.

The User Confirmation Prompt

To prevent malicious or unwanted extensions from hijacking the browser without the user's knowledge, Chromium implements a safeguard. The first time you open a New Tab after a new extension takes control, the browser displays a notification dialog near the top right of the screen.

This prompt informs you that a specific extension has changed what page is shown when you open a new tab. You are given two choices:

  • Keep it: Confirms the new extension as the active New Tab controller.
  • Change it back: Reverts the New Tab page to its previous state (either the previously controlling extension or the default Chromium page) and disables the new extension entirely.

Fallback Behavior

Chromium maintains a history—or a stack—of extensions that have requested the New Tab override. If you disable or uninstall the extension currently controlling the New Tab page, the browser does not necessarily revert to the default Chromium page. Instead, control falls back to the second-most recently enabled extension that has a New Tab override declared in its manifest.

The default Chromium New Tab page will only return if all extensions attempting to override it are either disabled or uninstalled.

How to Manually Choose the Winning Extension

Chromium does not provide a dedicated dropdown menu in its settings to select which active extension controls the New Tab page, assuming you want to keep both extensions enabled for their other features.

To manually force a specific extension to take control of the New Tab page while keeping the conflicting extension active, follow these steps:

  1. Navigate to chrome://extensions in your address bar.
  2. Locate the extension you want to control the New Tab page.
  3. Toggle the switch to Disable the extension.
  4. Toggle the switch back to Enable the extension.

Because this action makes your preferred extension the "most recently enabled," Chromium immediately grants it priority over the New Tab page, pushing the conflicting extension's override into the background.