Understanding Transaction Failures

When interacting with the Ethereum blockchain using Ethers.js, a transaction may fail for various reasons, including insufficient funds, exceeding the gas limit, or a revert condition in a smart contract. It's crucial to handle these failures gracefully to provide users with meaningful feedback and potentially allow them to retry the transaction.

Common Reasons for Transaction Failures

  • Insufficient Funds: The sender's account does not have enough Ether to cover the transaction amount and gas fees.
  • Gas Limit Exceeded: The transaction requires more gas than specified in the gas limit.
  • Smart Contract Reverts: A function call in a smart contract fails due to a condition not being met (e.g., a require statement fails).
  • Network Issues: Problems with connecting to the Ethereum network can also lead to transaction failures.

What to Do When a Transaction Fails

When a transaction fails, you can take several actions:

  • Log the error message for debugging purposes.
  • Provide user-friendly feedback to the user, explaining why the transaction failed.
  • Allow the user to adjust parameters (e.g., increase gas limit) and retry the transaction.

Sample Code for Handling Failed Transactions

Below is a complete HTML example demonstrating how to handle failed transactions when sending Ether using Ethers.js: 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Ethers.js Failed Transaction Handling Example</title>
    <script src="https://cdn.jsdelivr.net/npm/ethers@5.7.0/dist/ethers.umd.min.js"></script>
</head>
<body>
    <h1>Send Ether with Failed Transaction Handling</h1>
    <input type="text" id="recipientInput" placeholder="Enter recipient address" />
    <input type="number" id="amountInput" placeholder="Enter amount in ETH" />
    <input type="text" id="privateKeyInput" placeholder="Enter your private key" />
    <button id="sendButton">Send Ether</button>
    <pre id="transactionInfo"></pre>

    <script>
        async function sendEther() {
            const provider = new ethers.providers.Web3Provider(window.ethereum);
            const recipient = document.getElementById('recipientInput').value;
            const amount = document.getElementById('amountInput').value;
            const privateKey = document.getElementById('privateKeyInput').value;

            // Create a wallet instance
            const wallet = new ethers.Wallet(privateKey, provider);

            // Create a transaction object
            const tx = {
                to: recipient,
                value: ethers.utils.parseEther(amount), // Convert amount to Wei
                gasLimit: 21000 // Set a gas limit (you can adjust this as needed)
            };

            try {
                // Send the transaction
                const transactionResponse = await wallet.sendTransaction(tx);
                document.getElementById('transactionInfo ').innerText = "Transaction Sent: " + transactionResponse.hash;

                // Wait for confirmation
                const receipt = await transactionResponse.wait();
                document.getElementById('transactionInfo').innerText += "\\nTransaction Confirmed in Block: " + receipt.blockNumber;
            } catch (error) {
                // Handle the error
                document.getElementById('transactionInfo').innerText = "Transaction Failed: " + error.message;

                // Additional logic to allow user to retry
                if (error.code === 'INSUFFICIENT_FUNDS') {
                    document.getElementById('transactionInfo').innerText += "\\nPlease ensure you have enough Ether.";
                } else if (error.code === 'TRANSACTION_REPLACED') {
                    document.getElementById('transactionInfo').innerText += "\\nTransaction was replaced. Check your transaction history.";
                } else {
                    document.getElementById('transactionInfo').innerText += "\\nAn unexpected error occurred.";
                }
            }
        }

        document.getElementById('sendButton').onclick = sendEther;
    </script>
</body>
</html>

Conclusion

Handling failed transactions in Ethers.js is essential for providing a smooth user experience. By understanding the common reasons for failures and implementing appropriate error handling, you can guide users through resolving issues and retrying transactions effectively.