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

# Error.getSelector

> Compute the 4-byte selector for a custom error

## Overview

`Error.getSelector` returns the first 4 bytes of the keccak256 hash of the error signature.

## Quick Start

```typescript theme={null}
import { Abi } from '@tevm/voltaire/Abi';
import { Hex } from '@tevm/voltaire/Hex';

const InsufficientBalance = {
  type: 'error',
  name: 'InsufficientBalance',
  inputs: [
    { type: 'uint256', name: 'balance' },
    { type: 'uint256', name: 'required' }
  ]
} as const;

const selector = Abi.Error.getSelector(InsufficientBalance);
const selectorHex = Hex.fromBytes(selector);
```

## Notes

* Uses canonical types for signatures (e.g. `uint256`).
* Error selectors are 4 bytes, like function selectors.

## See Also

* [getSignature](/primitives/abi/error/get-signature) - Error signature string
* [Selectors](/primitives/abi/selectors) - Selector rules