How to fix MetaMask "Transaction failed" on Ethereum? (Gas Limit Fix)

Understanding Gas Limit Errors

1. Ethereum transactions require computational resources measured in gas units. When MetaMask displays 'Transaction failed', one frequent cause is an insufficient gas limit set manually or automatically by the wallet.

2. The gas limit defines the maximum amount of gas a transaction is allowed to consume. If the actual execution exceeds this value, the transaction reverts and fails—even if the user has sufficient ETH for fees.

3. Smart contract interactions, especially with complex DeFi protocols or NFT mints, often demand higher gas than simple ETH transfers. Default limits may not accommodate these operations.

4. Network congestion can indirectly affect gas estimation. During high-traffic periods, MetaMask’s auto-estimation sometimes underreports required gas due to stale or incomplete mempool data.

Manual Gas Limit Adjustment Steps

1. Open MetaMask and locate the pending or failed transaction in the activity tab. Click the three-dot menu and select “Edit” if the transaction is still unconfirmed.

2. Toggle “Advanced” to reveal gas parameters. Disable “Auto” for gas limit and input a custom value. For standard ERC-20 approvals, 65,000–100,000 is typical; for Uniswap swaps or complex contract calls, try 250,000–400,000.

3. Verify the new gas limit does not exceed the block gas limit (currently ~30 million). Values above 5 million are rarely necessary and may trigger rejection by some RPC endpoints.

4. Confirm the updated transaction. MetaMask will recalculate the total fee based on the new limit and current base fee + priority fee settings.

Using Etherscan to Diagnose Failures

1. Copy the transaction hash from MetaMask and paste it into Etherscan’s search bar. Navigate to the “State” or “Internal Txns” tab to view execution traces.

2. Look for the “Status” field—“Fail” indicates revert. Scroll down to “Input Data” and cross-reference with the contract’s ABI to identify which function call triggered the error.

3. Check the “Gas Used by Transaction” value. If it equals the gas limit exactly, the failure was almost certainly due to out-of-gas—not a logic error in the contract.

4. Use Etherscan’s “Verify and Publish” feature to inspect verified source code. Revert reasons like “SafeMath: subtraction overflow” or “transfer amount exceeds balance” appear in decoded logs when available.

RPC Endpoint and Network Configuration

1. Switch MetaMask’s Ethereum network to a different RPC provider. Default Infura endpoints occasionally return inaccurate gas estimates. Alternatives include Alchemy, QuickNode, or Cloudflare Ethereum Gateway.

2. Ensure the selected network matches the intended chain ID. Sending a transaction intended for Ethereum Mainnet to a testnet RPC—or vice versa—causes immediate failure before gas evaluation.

3. Clear MetaMask’s transaction history cache by navigating to Settings → Advanced → Reset Account. This forces fresh nonce and gas estimation on next interaction.

4. Disable browser extensions that inject scripts into dApps. Some ad blockers or privacy tools interfere with web3 provider injection, leading to corrupted gas estimation payloads.

Frequently Asked Questions

Q: Why does increasing gas limit not always fix the 'Transaction failed' error?Because some failures stem from contract-level reverts—not resource exhaustion. Examples include insufficient token allowance, expired deadlines, or failed ownership checks. These occur regardless of gas allocation.

Q: Can I reuse the same nonce after a failed transaction?Yes. A reverted transaction consumes no gas but still increments the sender’s nonce. Submitting a new transaction with the same nonce—and higher gas limit or corrected parameters—will replace the failed one if signed with the same private key.

Q: Does MetaMask’s “Speed Up” function always resolve gas-related failures?No. Speed Up only increases priority fee and optionally gas price—it does not modify the gas limit. If the original limit was too low, Speed Up alone cannot prevent an out-of-gas revert.

Q: How do I find the optimal gas limit without overpaying?Use Etherscan’s “Gas Tracker” to review median gas used for similar contract methods. For custom interactions, test on Sepolia first using identical calldata. Monitor the “Gas Used” field in successful testnet transactions as a baseline.