A wallet or dApp rejects your ETH or token transfer with nonce too low, sometimes “already known”. Funds are not lost: the wallet used a sequence number that the network has already consumed.
Why it happens
Each Ethereum account has a nonce counter, and every new transaction must use the next value (ethereum.org: accounts). Typical causes are the same address open on two devices, a stale local cache after restoring a wallet, a recently replaced transaction, or a bot keeping its own counter. A gap in nonces causes the opposite symptom — a pending transaction (missing nonce).
Fix
- Check the explorer: maybe the payment already went through.
- Note the nonce of the latest outgoing transaction; the next must be one higher.
- Reset the wallet's local activity cache (MetaMask: Clear activity tab data in advanced settings) or reconnect the account.
- Close other instances and sign again.
Hardware wallets are affected the same way: the device signs whatever nonce the companion app passes, so refresh the app first.
Prevention is simple: use one address from one device at a time, wait for full sync after restoring a wallet, and do not queue several unconfirmed transfers at once.
Watch for compromise
If the explorer shows outgoing transactions you did not send, move remaining funds to a new wallet. Before paying a swap order such as ETH to BTC again, confirm that the first payment did not already arrive; if it confirmed after the order expired, contact support with the order number and hash.
FAQ
Does nonce too low mean my ETH is gone?
No. The node simply refused a transaction with a used number. Sign again with the correct nonce.
Is clearing MetaMask activity safe?
It resets local history only; keys and balances stay on-chain. Keep your seed backup anyway.