Web3: gas required exceeds allowance (0)
The node simulated the transaction and found the sender cannot cover it, so the allowance it reports is the gas the balance affords, often zero. Despite the wording it is rarely a gas limit problem: the account is empty, or it is the wrong account, or the wrong chain is selected in the wallet.
Quick fix
Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.
# Check the balance on the chain you are actually sending to
cast balance 0xYourAddress --rpc-url https://ethereum-rpc.publicnode.com
cast chain-id --rpc-url https://ethereum-rpc.publicnode.com
// Estimate first: the revert reason often explains the real failure
const gas = await contract.transfer.estimateGas(to, amount);
// A payable call needs value plus gas, not value alone
await contract.mint(1, { value: ethers.parseEther("0.05") });
# On an L2 the fee has an L1 data component the wallet may not show
cast estimate --rpc-url $L2_RPC 0xContract "transfer(address,uint256)" 0xTo 1
# Same message with a funded account usually means the call reverts on chain,
# so simulate it against a fork before blaming gas
anvil --fork-url $RPC_URLHow to diagnose Web3 errors
Web3 errors are unusually terse because the EVM reports failure without explanation by default. execution reverted means a require or revert triggered. The reason string is present in the return data but most libraries discard it. Nonce errors reflect the strict sequential ordering of transactions per account, so a stuck transaction blocks every one behind it.
If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.
- Simulate before sending:
eth_callagainst the same block returns the revert reason string that a submitted transaction hides. - Use a transaction tracer (Tenderly, Foundry's
cast run, or a node'sdebug_traceTransaction) to see the exact opcode and contract where execution reverted. - For nonce errors, query the account's pending nonce (
eth_getTransactionCountwith thependingtag) rather than tracking it locally. - To replace a stuck transaction, resend with the same nonce and a materially higher gas price: most nodes require at least a 10% increase.
- Check the chain ID matches the network you intend. Signing for the wrong chain produces confusing rejection messages.
Tools worth reaching for
cast (Foundry)eth_call simulationTenderly / block explorer tracerdebug_traceTransaction
Authoritative references
Primary documentation for this error, worth reading before applying any fix in production.
Related Web3 errors
- Web3: execution revertedThe smart contract reverted. Solidity custom errors or revert strings often explain the exact…
- Web3: insufficient funds for gas * price + valueThe wallet lacks enough native token to pay transaction value plus gas. This is separate from…
- Web3: intrinsic gas too lowThe gas limit on the transaction is below the minimum the EVM charges before executing any…
- Web3: max fee per gas less than block base feeThe node rejected the transaction because its maxFeePerGas is below the base fee of the next…
- Web3: missing revert data in call exception (CALL_EXCEPTION)The call failed without a reason string, which usually means there is no contract at that…
- Web3: nonce too low / replacement transaction underpricedThe transaction nonce has already been mined, or a replacement transaction did not increase…
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Something missing or wrong?
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