> ## Documentation Index
> Fetch the complete documentation index at: https://docs.portalhq.io/llms.txt
> Use this file to discover all available pages before exploring further.

# eth_signUserOperation

> Sign an ERC-4337 UserOperation without broadcasting it.

## Function Signature

```dart theme={null}
Future<PortalProviderResponse> request({
  required String chainId,
  required String method,  // 'eth_signUserOperation'
  required List<Object?> params,
  String? signatureApprovalMemo,
})
```

## Description

Signs an ERC-4337 UserOperation using the client's MPC key without broadcasting it to the network. This method is invoked via `portal.request()` with the method set to `eth_signUserOperation`. The signed UserOperation can then be submitted through a separate backend (e.g., Pimlico or a custom bundler endpoint).

<Warning>
  This method requires the client to be created with [Account Abstraction](../../../resources/account-abstraction) enabled (`isAccountAbstracted: true`). Non-AA clients will receive a `METHOD_UNSUPPORTED` error.
</Warning>

## Parameters

The `params` array takes a single object with the following fields:

| Parameter              | Type     | Required | Description                                 |
| ---------------------- | -------- | -------- | ------------------------------------------- |
| `to`                   | `String` | Yes      | The recipient or contract address           |
| `value`                | `String` | No       | Value in wei (hex-encoded)                  |
| `data`                 | `String` | No       | Calldata (hex-encoded)                      |
| `gas`                  | `String` | No       | Gas limit (hex-encoded)                     |
| `maxFeePerGas`         | `String` | No       | Max fee per gas for EIP-1559 (hex-encoded)  |
| `maxPriorityFeePerGas` | `String` | No       | Max priority fee for EIP-1559 (hex-encoded) |
| `nonce`                | `String` | No       | Transaction nonce (hex-encoded)             |

## Returns

**`PortalProviderResponse`** - An object containing:

| Property | Type      | Description                                                   |
| -------- | --------- | ------------------------------------------------------------- |
| `result` | `dynamic` | A hex-encoded JSON string containing the signed UserOperation |
| `error`  | `dynamic` | Error information if the call failed                          |

## Example

```dart theme={null}
import 'package:portal_flutter/portal_flutter.dart';

final portal = Portal();

// Sign a UserOperation on Sepolia testnet
final result = await portal.request(
  chainId: 'eip155:11155111',
  method: 'eth_signUserOperation',
  params: [
    {
      'to': '0xRecipientAddress',
      'value': '0x0',
      'data': '0x',
    }
  ],
);

if (result.error != null) {
  print('Error: ${result.error}');
} else {
  print('Signed UserOp: ${result.result}');
}
```

### With EIP-1559 Gas Parameters

```dart theme={null}
final result = await portal.request(
  chainId: 'eip155:11155111',
  method: 'eth_signUserOperation',
  params: [
    {
      'to': '0xRecipientAddress',
      'value': '0xDE0B6B3A7640000', // 1 ETH in wei
      'data': '0x',
      'maxFeePerGas': '0x3B9ACA00',
      'maxPriorityFeePerGas': '0x3B9ACA00',
    }
  ],
);
```

## Errors

| Code                 | Description                                          |
| -------------------- | ---------------------------------------------------- |
| `METHOD_UNSUPPORTED` | The client does not have Account Abstraction enabled |
| `NOT_INITIALIZED`    | Portal was not initialized                           |
| `RPC_ERROR`          | The RPC call returned an error                       |

## Related

* [Sign a user operation guide](../guide/sign-a-user-operation)
* [request](./request)
* [sendTransaction](./sendtransaction)
* [Account Abstraction](../../../resources/account-abstraction)