How to fix MetaMask freezing when opening on Firefox?

Browser Compatibility Verification

1. Confirm that Firefox is updated to version 151 or higher, as earlier versions may exhibit instability with MetaMask’s Ethereum provider injection.

2. Disable all non-essential extensions except MetaMask to rule out interference from ad blockers, privacy tools, or script injectors.

3. Launch Firefox in Safe Mode by holding Shift while opening the browser and selecting “Start in Safe Mode” to test whether add-ons or themes cause freezing.

4. Check if the issue persists when accessing MetaMask only on HTTPS websites—MetaMask no longer injects ethereum or web3 objects into file:// protocol pages.

Web3 Provider Configuration

1. Open Firefox Developer Tools (Ctrl+Shift+I), navigate to the Console tab, and type ethereum to verify the provider object exists without throwing errors.

2. If ethereum returns undefined, the MetaMask script injection has failed—reinstall MetaMask from the official addons.mozilla.org page.

3. Avoid using legacy web3 initialization patterns; instead rely on ethereum.request({ method: 'eth_accounts' }) for account retrieval.

4. Ensure the DApp frontend does not call new Web3(ethereum) before confirming ethereum.isMetaMask === true to prevent race conditions.

Firefox Security & Privacy Settings

1. Navigate to about:config, search for dom.webnotifications.enabled, and set it to true—some MetaMask popups depend on notification permissions.

2. Disable Enhanced Tracking Protection temporarily for the current site by clicking the shield icon in the address bar and selecting “Disable Protection for This Site.”

3. In about:config, verify privacy.resistFingerprinting is set to false—enabling fingerprint resistance can block Ethereum provider detection.

4. Set network.http.referer.XOriginTrimmingPolicy to 0 to prevent referer stripping that may disrupt MetaMask’s internal iframe communication.

Cache and Profile Integrity

1. Clear site data specifically for metamask.io and any DApp domains using Settings > Privacy & Security > Cookies and Site Data > Manage Data.

2. Create a new Firefox profile via firefox.exe -P (Windows) or firefox -P (macOS/Linux) and install only MetaMask to isolate profile corruption.

3. Delete the storage/default/ subdirectory inside the Firefox profile folder if persistent freezing occurs after restarts.

4. Disable hardware acceleration under Settings > General > Performance > Use recommended performance settings to eliminate GPU-related hangs during wallet popup rendering.

Common Questions and Answers

Q: Why does MetaMask show “Connecting…” indefinitely on Firefox but works fine in Chrome?A: Firefox enforces stricter Content Security Policy (CSP) rules and may block inline scripts used by older DApp frontends. Verify the DApp uses ethereum rather than deprecated window.web3 and serves assets over HTTPS with valid certificates.

Q: Can I use MetaMask with Firefox’s Private Browsing mode?A: Yes, but only if “Remember browsing history” is enabled in Private Browsing settings. MetaMask requires persistent session storage to retain connection state across tabs.

Q: Is DownThemAll! compatible with MetaMask-enabled sites?A: DownThemAll! 4.14.3 does not interfere with MetaMask since it operates at the network layer and does not modify DOM or inject scripts into Ethereum-aware pages.

Q: Does Firefox 151’s enhanced tracking protection break MetaMask’s popup window?A: It may suppress the popup if classified as a tracker. Manually allow popups for the current domain via the address bar shield icon or disable ETP for that site.