Nonce Too Low Error Explainer

WHAT IT DOES

Nonce Too Low Error Explainer takes a pending or recent transaction hash and determines whether it will fail because its nonce is behind the current account nonce. Every Ethereum account has a nonce—a sequential number that increments with each transaction sent from that address. Transactions must be processed in strict nonce order; a transaction with a nonce lower than the current chain nonce will be immediately rejected. This tool reads the transaction's nonce from the calldata, then fetches the sender's current chain nonce (the count of already-mined transactions) and the pending nonce (which includes unconfirmed transactions). It compares these values and also scans for other pending transactions from the same sender to detect conflicts—such as two transactions with the same nonce (a double-spend attempt) or a gap in nonces that would cause later transactions to wait indefinitely. The output includes the transaction nonce, the chain nonce, the pending nonce, any conflicting transactions, and a plain‑language explanation of what is wrong and how to fix it—such as waiting for pending transactions to clear, replacing a transaction with a higher nonce, or canceling stuck transactions.

HOW TO USE

Paste any transaction hash (pending or already mined) into the input field, select the network, and click "Check nonce". The tool connects to your wallet via the EVM bridge (read‑only; it never signs or sends anything) to fetch the transaction details and the sender's current nonce state. It reads the transaction's nonce from the transaction object, then fetches the chain nonce (transactions already mined) and the pending nonce (including unconfirmed) using eth_getTransactionCount. It also queries the pending block to list all pending transactions from the same sender, checking for nonce conflicts or gaps. The AI layer generates a plain‑English summary: whether the transaction will fail due to a nonce that is too low, and what action the user should take. You can click on the transaction hash to view it on the block explorer.

PENDING BLOCK SCAN WITH NONCE GAP DETECTION

Unlike simple nonce checkers that only compare against the chain nonce, this tool performs a comprehensive analysis of the sender's entire pending transaction queue. It fetches the pending block (eth_getBlockByNumber with "pending" flag) and iterates through all pending transactions from the same sender, recording their nonces. It then checks for three specific failure modes: (1) nonce too low—the transaction nonce is less than the chain nonce, meaning it will be rejected outright; (2) nonce conflict—two pending transactions share the same nonce, meaning only one will be mined and the other will fail; and (3) nonce gap—the transaction nonce is higher than the pending nonce by more than 1, meaning earlier transactions must be mined first, causing indefinite delay. The tool also tracks the gas prices of other pending transactions to detect "gas wars" where a transaction with a higher nonce has a higher gas price, potentially causing the lower-nonce transaction to be skipped. If any RPC call fails, it falls back to the next endpoint without stopping the scan.

WHAT IT CANNOT SEE

This tool cannot detect nonce issues that depend on off‑chain state (e.g., transactions that are dropped from the mempool and re‑submitted with different nonces by a relayer). It cannot predict when pending transactions from the same sender will be mined, which would change the nonce before this transaction is included—the check reflects the current state, not the future. It cannot verify that the sender intended to use the exact nonce being checked—the tool reads what is on‑chain, not the user's intent. It cannot detect nonce issues in contracts that use custom nonce tracking (e.g., EIP‑2612 permit nonces, or custom replay protection that is not based on transaction nonce). It cannot guarantee that resubmitting with a higher nonce will succeed if other pending transactions are re‑ordered or dropped. It cannot detect if the sender has accidentally submitted duplicate transactions with the same nonce and different payloads, which can lead to one being rejected, unless they are both visible in the pending block at the time of the check.

PLEASE NOTE

This tool works only for EVM‑compatible chains (Ethereum, Polygon, BSC, Arbitrum, Optimism, Avalanche C‑chain, etc.) and relies on the standard transaction nonce mechanism. It does not support custom nonce schemes used by some meta‑transactions or account abstraction contracts. All explanations are AI‑generated from data the app reads on‑chain—the AI synthesizes the nonce values, pending transaction list, and chain state into plain English, but it does not have special access to private contract logic or off‑chain data. Always review what you are actually signing in your wallet before approving any transaction; a nonce explanation does not replace your own verification of the transaction details, including the nonce and the target contract. This tool is provided free of charge, with no warranty of accuracy or completeness.