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

# CoFHE Errors Package

> Decode Solidity smart contract errors and resolve 'execution reverted' messages instantly with @fhenixprotocol/cofhe-errors

## Overview

When working with Solidity smart contracts, you've probably encountered cryptic error messages like:

```
Error: execution reverted: 0x118cdaa7
Transaction reverted without a reason string
execution reverted
```

These errors are frustrating because you only get a 4-byte error selector (e.g., `0x118cdaa7`) with no human-readable message. The `@fhenixprotocol/cofhe-errors` package provides **instant, human-readable error decoding** for CoFHE smart contracts.

<Card title="What's Inside" icon="box">
  * **53 custom errors** from **13 smart contracts**
  * Complete error signatures with parameter types
  * Source contract information
  * Fast CLI lookup tool
  * Programmatic JavaScript/TypeScript API
</Card>

## Quick Start

**No installation required!** Use `npx` to decode errors immediately:

```bash theme={null}
npx cofhe-errors 0x118cdaa7
```

**Output:**

```
Name:      OwnableUnauthorizedAccount
Selector:  0x118cdaa7
Signature: OwnableUnauthorizedAccount(address)
Source:    ACL
Inputs:    address
```

## Installation (Optional)

Only install if you need to import the error database programmatically in your code:

<CodeGroup>
  ```bash npm theme={null}
  npm install @fhenixprotocol/cofhe-errors
  ```

  ```bash yarn theme={null}
  yarn add @fhenixprotocol/cofhe-errors
  ```

  ```bash pnpm theme={null}
  pnpm add @fhenixprotocol/cofhe-errors
  ```
</CodeGroup>

## CLI Usage

### Decode an Error Selector

When you see "execution reverted: 0x...", decode it instantly:

```bash theme={null}
npx cofhe-errors 0x118cdaa7
```

### Search Errors by Name

Find errors when you know part of the error name:

```bash theme={null}
npx cofhe-errors --name Permission
```

**Output:**

```
0x4c40eccb PermissionInvalid_IssuerSignature (ACL)
0x8e143bf7 PermissionInvalid_RecipientSignature (ACL)
0xcbd3a966 PermissionInvalid_Disabled (ACL)
0xed0764a1 PermissionInvalid_Expired (ACL)
```

### List All Known Errors

Browse the complete error database:

```bash theme={null}
npx cofhe-errors --list
```

### JSON Output

Get JSON output for scripting and automation:

```bash theme={null}
npx cofhe-errors --json 0x118cdaa7
```

**Output:**

```json theme={null}
{
  "name": "OwnableUnauthorizedAccount",
  "selector": "0x118cdaa7",
  "signature": "OwnableUnauthorizedAccount(address)",
  "source": "ACL",
  "inputs": ["account"],
  "inputTypes": ["address"]
}
```

## Programmatic API

### JavaScript/TypeScript Usage

```javascript theme={null}
const errors = require('@fhenixprotocol/cofhe-errors/errors.json');

// Find error by selector
const error = errors.find(e => e.selector === '0x118cdaa7');
console.log(`Error: ${error.name}`);
console.log(`Signature: ${error.signature}`);

// Search by name
const permissionErrors = errors.filter(e =>
  e.name.toLowerCase().includes('permission')
);

// Get all errors from a specific contract
const aclErrors = errors.filter(e => e.source === 'ACL');
```

### TypeScript with Types

```typescript theme={null}
import errors from '@fhenixprotocol/cofhe-errors/errors.json';

interface SolidityError {
  name: string;
  selector: string;
  signature: string;
  source: string;
  inputs: string[];
  inputTypes: string[];
}

const error = errors.find(e => e.selector === '0x118cdaa7') as SolidityError;
```

### Error Monitoring Example

```javascript theme={null}
const errors = require('@fhenixprotocol/cofhe-errors/errors.json');

// Decode error from blockchain event
function decodeError(errorData) {
  const selector = errorData.slice(0, 10); // First 4 bytes
  const error = errors.find(e => e.selector === selector);

  if (error) {
    console.log(`Error: ${error.name}`);
    console.log(`Contract: ${error.source}`);
    console.log(`Signature: ${error.signature}`);
  }
}
```

## Error Coverage

The package includes errors from the following contracts:

| Contract                | Error Count |
| ----------------------- | ----------- |
| TaskManager             | 16          |
| ACL                     | 8           |
| SafeCast                | 4           |
| ERC1967Utils            | 4           |
| Errors                  | 4           |
| Ownable2StepUpgradeable | 4           |
| ECDSA                   | 3           |
| Strings                 | 3           |
| Common                  | 2           |
| UUPSUpgradeable         | 2           |
| Address                 | 1           |
| FHE                     | 1           |
| PlaintextsStorage       | 1           |

## How Error Selectors Work

Solidity custom errors use a 4-byte selector computed as:

```
selector = keccak256("ErrorName(type1,type2,...)").slice(0, 4)
```

**Example:**

```solidity theme={null}
error OwnableUnauthorizedAccount(address account);
```

Becomes:

* Signature: `OwnableUnauthorizedAccount(address)`
* Selector: `keccak256("OwnableUnauthorizedAccount(address)") = 0x118cdaa7...`
* First 4 bytes: `0x118cdaa7`

## Next Steps

* View the [complete error reference](/fhe-library/reference/cofhe-errors-reference) with all 53 errors
* Learn about [common errors](/fhe-library/core-concepts/common-errors) and troubleshooting
* Review [best practices](/fhe-library/introduction/best-practices) for FHE development