How to fix signature invalid error on Ethereum wrong chain ID
The "signature invalid" error on Ethereum is almost always a chain ID mismatch. It is not a broken wallet or a corrupted transaction. The error exists because of a protocol change introduced in 2016.
EIP-155 added a chain ID to every transaction signature. Before EIP-155, a signed transaction on Ethereum mainnet could be broadcast on any network that understood the same signing scheme. An attacker could take a mainnet transaction, broadcast it on a testnet or a compatible L2, and the receiving network would treat it as valid. That is a replay attack. Chain ID prevents it.
Every Ethereum-compatible network has a unique chain ID. Mainnet is 1. Sepolia testnet is 11155111. Arbitrum One is 42161. Optimism is 10. Polygon is 137. When you sign a transaction, your wallet encodes the destination network's chain ID into the signature. The network you send it to checks that chain ID against its own. If they do not match, the signature is rejected. That rejection is the "signature invalid" error.
The most common cause: your wallet is on the wrong network.
You might be looking at a dApp that expects Arbitrum. Your MetaMask is set to Ethereum mainnet. You sign a message or approve a transaction. The dApp sends that signed data to Arbitrum. Arbitrum reads the chain ID in the signature, sees it says 1 (the mainnet ID), and refuses it. The error appears.
How to fix it in MetaMask:
- Open MetaMask. Look at the network badge at the top left. It shows the current network name and chain ID.
- Check what network the dApp expects. Most dApps display this in the top bar or in a settings panel. Some dApps auto-prompt a network switch.
- If the dApp does not auto-prompt, switch MetaMask manually. Click the network dropdown. Find the correct network. If it is not listed, add it manually via a network RPC resource like Chainlist.
- Re-initiate the transaction or sign the message again. The new signature will include the correct chain ID.
How to fix it on a hardware wallet (Ledger, Trezor):
Hardware wallets do not remember what network you are on. They rely entirely on the wallet interface (MetaMask, Rabby) to define the chain ID. The fix is still to set the correct network in the interface before signing. Some hardware wallet apps, like Ledger Live, also have a "blind signing" setting. That setting does not fix a chain ID mismatch. It only allows signing transactions whose contract data cannot be decoded. You still need the correct network selected.
Second common cause: a signed message was created on one chain and verified on another.
Some dApps ask you to sign a message to prove wallet ownership, not to send funds. That signed message also contains a chain ID. If you sign on mainnet and then open the same dApp on Arbitrum, the dApp might try to verify that message using Arbitrum's chain ID. It will fail. The error is the same: "signature invalid." The fix is to re-sign while the wallet is connected to the chain where verification happens.
How this protects you:
The system is symmetrical. It also prevents you from accidentally spending mainnet funds on a testnet. If you build a transaction worth 1 ETH on mainnet, sign it, and then broadcast it on Sepolia by mistake, Sepolia checks the chain ID, finds 1 instead of its own 11155111, and discards the transaction. Your 1 ETH stays on mainnet.
The same protection applies to L2s. A transaction signed for Arbitrum cannot be broadcast on Optimism, even if both use the same underlying Ethereum infrastructure. The chain IDs are different.
What not to do:
Do not disable chain ID verification in your wallet. Some older tools and scripts have a flag to skip chain ID checks so they can reuse signatures across networks. That flag exists only for testing. Using it in production removes replay protection entirely. If you are a developer, chain ID checks should stay on in anything that touches real funds.
If the error persists after checking the chain ID, the problem might be something else. A genuinely expired nonce. A corrupted signing request. Or a wallet that needs to be reconnected. But for the "signature invalid" error specifically, the chain ID is the first thing to check, and it resolves the issue in the vast majority of cases.
Biden Coin (BIDEN) trades on Ethereum at the contract address 0x9E59A081320Ddb046d74a106335cA6B84EadC067. It launched via Uniswap on April 27, 2025. As of August 31, 2026, the pair has 30 distinct liquidity pools, with one active Uniswap pair carrying about $375,000 in liquidity. Daily trading volume was under $20. If you interact with this token or any token, make sure your wallet is on Ethereum mainnet, chain ID 1. A mismatched chain ID will give you the same "signature invalid" error. The solution is the same: check the network, switch it, re-sign.
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