MetaMask Nonce Too Low: What the Error Means and How to Fix It

"Nonce too low" means your wallet tried to send a transaction using a number that is already taken. Every transaction from your address carries a counter - the nonce - starting at 0 and rising by one each time. Once a transaction with number 47 has confirmed, seat 47 is occupied forever, and Ethereum rejects anything else that tries to sit in it. Nothing is lost when you see this error. The transaction simply never left.

Why does MetaMask get the number wrong?

Usually because MetaMask and the network disagree about how many transactions you have sent. MetaMask keeps a local count, and that count can fall behind - after you send from the same address in a different wallet such as Rabby, after using the same seed phrase on a second computer, or after an RPC node hands back stale data. Think of it as a hotel receptionist working from yesterday's guest list: she offers you room 47, and room 47 was let last night.

The three usual causes

• You typed the nonce yourself. Custom nonce is on, you entered the number of a transaction that has since confirmed, and the seat is gone.
• The same address is live in two places. A second wallet, or MetaMask on a laptop and a phone, each keeping its own count.
• Your network connection is stale. A busy public RPC endpoint can report an out-of-date transaction count for a minute or two.

How to clear it

Start with the cheapest fix: close MetaMask, reopen it, and switch networks and back - Ethereum to Arbitrum and return. That forces a fresh reading of your real transaction count, and most of the time the error disappears. If it persists, clear the local activity data, which rebuilds the count from the chain. If you set the nonce by hand, look up your address on Etherscan, read the highest confirmed nonce, and use the next number up - or just turn custom nonce off and let the wallet decide.

The habit worth keeping: never run the same address in two wallets at once if you can avoid it, because that is what produces this error most often. If the number you want is still in use by something pending rather than confirmed, that is a different job - customising the nonce covers it, and resetting the nonce explains what a reset can and cannot do.