> ## Documentation Index
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# Only replay-protected (EIP-155) transactions allowed over RPC

> Fix the EVM node 'only replay-protected (EIP-155) transactions allowed over RPC' error by adding chainId to your signed transaction. Includes examples in ethers.js, viem, and web3.py.

**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](https://eips.ethereum.org/EIPS/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](https://chainlist.org/).

<CodeGroup>
  ```typescript ethers.js theme={"system"}
  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
  });
  ```

  ```typescript viem theme={"system"}
  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"),
  });
  ```

  ```python web3.py theme={"system"}
  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)
  ```
</CodeGroup>

<Note>
  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.
</Note>

## See also

* [EIP-155: Simple replay attack protection](https://eips.ethereum.org/EIPS/eip-155)
* [chainlist.org](https://chainlist.org/) — registry of EVM chain IDs
* [Error reference](/docs/error-reference)