TLDR:
- EVM nodes refuse to broadcast legacy (pre-EIP-155) transactions because they could be replayed on other EVM chains.
- The fix: include
chainId in the transaction object before signing.
- All modern signing libraries do this automatically when you pass
chainId (ethers.js, viem) or set the network/wallet to a specific chain (web3.py with a chain-aware wallet).
The error
You try to send a raw transaction through an EVM node and get:
only replay-protected (EIP-155) transactions allowed over RPC
Cause
EIP-155 made the chain ID part of the signed transaction so a signature for Ethereum mainnet can’t be replayed as-is on, say, BNB Smart Chain. Most modern EVM clients refuse to accept non-EIP-155 transactions over public RPC. If your signing code doesn’t include chainId, the resulting transaction is “legacy” pre-EIP-155 and the node rejects it.
Solution
Include chainId in the transaction object before signing. The value is the numeric chain ID of the target network — look it up on chainlist.org.
import { Wallet, JsonRpcProvider, parseEther, parseUnits } from "ethers";
const provider = new JsonRpcProvider("https://ethereum-mainnet.core.chainstack.com/AUTH_KEY");
const wallet = new Wallet(process.env.PRIVATE_KEY!, provider);
// ethers picks up chainId automatically from the provider.
// For manual construction, include it explicitly:
const tx = await wallet.sendTransaction({
to: "0xRecipientAddress",
value: parseEther("0.1"),
gasLimit: 21000,
maxFeePerGas: parseUnits("50", "gwei"),
maxPriorityFeePerGas: parseUnits("2", "gwei"),
chainId: 1, // Ethereum mainnet
});
import { createWalletClient, http, parseEther, parseGwei } from "viem";
import { mainnet } from "viem/chains";
import { privateKeyToAccount } from "viem/accounts";
const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`);
const client = createWalletClient({
account,
chain: mainnet, // chain object carries the chain ID
transport: http("https://ethereum-mainnet.core.chainstack.com/AUTH_KEY"),
});
const hash = await client.sendTransaction({
to: "0xRecipientAddress",
value: parseEther("0.1"),
maxFeePerGas: parseGwei("50"),
maxPriorityFeePerGas: parseGwei("2"),
});
from web3 import Web3
w3 = Web3(Web3.HTTPProvider("https://ethereum-mainnet.core.chainstack.com/AUTH_KEY"))
account = w3.eth.account.from_key(PRIVATE_KEY)
tx = {
"to": "0xRecipientAddress",
"value": w3.to_wei(0.1, "ether"),
"gas": 21000,
"maxFeePerGas": w3.to_wei(50, "gwei"),
"maxPriorityFeePerGas": w3.to_wei(2, "gwei"),
"nonce": w3.eth.get_transaction_count(account.address, "latest"),
"chainId": w3.eth.chain_id, # fetched once and reused
}
signed = account.sign_transaction(tx)
tx_hash = w3.eth.send_raw_transaction(signed.raw_transaction)
In ethers.js and viem, chainId is taken from the provider/chain object — you usually don’t have to set it manually. The error typically shows up when you’re hand-crafting a transaction or using a low-level signer that doesn’t have a chain context bound.
See also
