How to fix MetaMask not connecting to Uniswap after browser update?

Browser Extension Conflicts

1. After a browser update, MetaMask may lose permission to inject scripts into decentralized applications. Navigate to chrome://extensions in Chrome or edge://extensions in Edge, locate MetaMask, and toggle on “Allow access to file URLs” and “Site access” set to “On all sites”.

2. Some updated browsers enforce stricter content security policies that block third-party script injection. Disable any ad blockers, privacy extensions like uBlock Origin or Privacy Badger during Uniswap interaction, as they often intercept Web3 provider initialization.

3. Brave Browser users must manually disable Shields for app.uniswap.org. Go to brave://settings/shields, find the site, and switch Shields to “Disabled”. Also verify that “Web3 API” is enabled under “Brave Wallet” settings.

4. Firefox users encountering “window.ethereum is undefined” should confirm that MetaMask is selected as the default wallet in about:config by setting “web3.enable” to true and restarting the browser.

RPC Network Configuration Reset

1. Browser updates sometimes reset custom RPC configurations. Open MetaMask Settings → Networks → Add Network → Custom RPC, and re-enter the correct parameters for Ethereum Mainnet: Network Name “Ethereum Mainnet”, New RPC URL “https://cloudflare-eth.com”, Chain ID 1, Symbol ETH, Block Explorer URL “https://etherscan.io”.

2. If using Uniswap v4 on Unichain, ensure Chain ID is set to 1301 and RPC URL matches “https://rpc.unichain.org”. A mismatch here causes immediate connection failure with no visible error in UI.

3. MetaMask’s “Privacy Mode” interferes with Uniswap’s provider detection logic. Disable it in Settings → Advanced → toggle off “Privacy Mode”, then hard-refresh Uniswap with Ctrl+Shift+R (Windows) or Cmd+Shift+R (Mac).

4. Legacy networks like Ropsten or Rinkeby are automatically removed after major browser updates. Confirm Uniswap is not attempting to connect to deprecated testnets by checking the network selector dropdown in MetaMask’s top bar.

Local Storage & Cache Corruption

1. Updated browsers may invalidate IndexedDB entries used by MetaMask to store account state. Press F12, go to Application → Storage → Clear site data for metamask.io and app.uniswap.org separately.

2. Corrupted transaction history can stall provider handshake. In MetaMask Settings → Advanced → “Reset Account”, which resets the nonce counter and forces resynchronization with the current chain head.

3. Chrome’s new “Storage Partitioning” feature isolates extension storage per origin. To restore compatibility, go to chrome://flags/#third-party-storage-partitioning and disable the flag, then relaunch the browser.

4. Old service workers from prior Uniswap versions may hijack fetch requests. Visit app.uniswap.org, open DevTools → Application → Service Workers, and click “Unregister” for all listed workers before reloading.

WalletConnect v2 Protocol Mismatch

1. Uniswap v4 exclusively uses WalletConnect v2 SDK, while older MetaMask versions rely on v1. Confirm MetaMask is updated to version 12.12.0 or higher — check via Settings → About MetaMask.

2. If connecting via QR code, ensure the mobile MetaMask app also runs v12.12.0+. Out-of-sync versions cause silent handshake failures where the QR remains static and no pairing event fires.

3. WalletConnect session persistence fails when browser local storage keys change post-update. Delete all entries starting with “wc@2” in Local Storage via DevTools → Application → Local Storage → app.uniswap.org.

4. Some updates break cross-origin iframe communication required for WalletConnect modals. Launch Uniswap in an incognito window first to validate whether enterprise policies or group policies are interfering.

Frequently Asked Questions

Q1: Why does MetaMask show “Connected” but Uniswap displays “Connect Wallet”?That indicates a provider handshake completed but Uniswap failed to read account information. Check console logs for “No accounts found” errors — usually caused by MetaMask’s account being locked or requiring re-authentication.

Q2: Can I use MetaMask on Uniswap if I’m on Firefox ESR?Yes, but only if Firefox ESR version is 115.12.0esr or newer. Older ESR builds lack support for the EIP-1193 event emitter standard required by Uniswap v4’s provider interface.

Q3: Does enabling “Snapshots” in MetaMask affect Uniswap connectivity?Yes. Snapshot functionality introduces asynchronous account enumeration that breaks Uniswap’s synchronous provider polling. Disable Snapshots in Settings → Advanced → toggle off “Enable Snapshots”.

Q4: Why does Uniswap work on mobile but not desktop after Chrome update?Chrome 125+ introduced stricter SameSite cookie enforcement for iframe contexts. Desktop Uniswap embeds MetaMask’s provider within an iframe; mobile uses native deep linking. Bypass by disabling “SameSite by default cookies” flag at chrome://flags/#same-site-by-default-cookies.