How to clear pending transactions in MetaMask? (Nonce Management)

Understanding Transaction Nonce in Ethereum

1. Every Ethereum transaction carries a unique sequential number called a nonce, assigned by the sender’s account.

2. The nonce starts at zero for the first transaction and increments by one with each subsequent transaction sent from that address.

3. Nodes reject transactions with nonces lower than the current account nonce or those skipping a number in the sequence.

4. When a transaction remains pending, it occupies a specific nonce slot, blocking all higher-nonce transactions from confirmation.

5. MetaMask relies on this deterministic ordering to queue and broadcast transactions — misaligned nonces directly cause stuck transactions.

Identifying Pending Transactions in MetaMask

1. Open MetaMask and navigate to the activity tab to view recent transaction history.

2. Look for entries marked as “Pending” — these are unconfirmed and still propagating across the network.

3. Click on a pending transaction to reveal its details, including the exact nonce value used.

4. Cross-check the displayed nonce against your latest confirmed transaction using a block explorer like Etherscan.

5. If multiple pending items appear, they likely occupy consecutive nonces — for example, nonce 127, 128, and 129 — creating a cascade failure.

Canceling a Stuck Transaction

1. In MetaMask, locate the pending transaction and click the three-dot menu next to it.

2. Select “Cancel” — this triggers MetaMask to broadcast a new transaction with the same nonce but zero value sent to the sender’s own address.

3. Set gas price slightly above the current network average to ensure faster inclusion; use the built-in gas estimator or consult EthGasStation.

4. Confirm the cancellation transaction using your wallet password or hardware device prompt.

5. Once mined, the original pending transaction becomes invalid, freeing up that nonce for reuse.

Speeding Up a Pending Transaction

1. Instead of canceling, choose “Speed Up” from the same three-dot menu adjacent to the pending entry.

2. MetaMask pre-fills a new transaction with identical parameters except for an increased gas fee.

3. The new transaction uses the same nonce, effectively replacing the slower version via Ethereum’s replacement rule.

4. Adjust the max fee per gas to at least 10–15% higher than the original if congestion persists.

5. Sign and submit — the network prioritizes the higher-fee version, rendering the earlier attempt orphaned upon confirmation.

Frequently Asked Questions

Q: Can I cancel a transaction after it has been confirmed? No. Once included in a block, Ethereum transactions are irreversible and cannot be altered or removed.

Q: Why does MetaMask sometimes show “Unknown error” when trying to cancel? This typically occurs when the node MetaMask connects to fails to return accurate pending transaction data or when the transaction has already been dropped from the mempool.

Q: What happens if I manually set a nonce lower than my current account nonce? The transaction will be rejected outright by nodes — it violates Ethereum’s state transition rules and never enters the mempool.

Q: Does changing networks in MetaMask affect my nonce count? No. Nonces are account-specific and chain-specific. Your Ethereum Mainnet nonce is independent from your Polygon or Arbitrum nonce — they do not interfere.