# Error Reference

All error codes thrown by the CEVEX SDK and how to handle them.

***

## Error Class

```typescript
import { CevexError, ErrorCode } from '@cevex/sdk'

try {
  const result = await verifier.verify(signed)
} catch (err) {
  if (err instanceof CevexError) {
    console.log(err.code)     // ErrorCode enum value
    console.log(err.message)  // Human-readable description
  }
}
```

***

## Error Codes

| Code                   | Description                                              | How to handle                                                                       |
| ---------------------- | -------------------------------------------------------- | ----------------------------------------------------------------------------------- |
| `IDENTITY_NOT_FOUND`   | No agent registered at this address on the Base registry | Check the agent address is correct and was provisioned on the right network         |
| `IDENTITY_REVOKED`     | The agent identity has been permanently revoked          | Reject the action. The identity cannot be reactivated.                              |
| `SIGNATURE_INVALID`    | Lattice verification failed                              | The signature does not match the message and public key. Reject the action.         |
| `NONCE_REPLAY`         | The nonce has been seen before                           | The message is a replay. Reject the action.                                         |
| `SCHEME_MISMATCH`      | Signature scheme does not match the registered scheme    | The signature was produced with a different scheme than the one registered on-chain |
| `REGISTRY_UNAVAILABLE` | Could not reach the Base registry                        | Retry with backoff or use a cached public key if available                          |
| `ENTROPY_FAILURE`      | Hardware QRNG health test failed                         | Do not proceed. The entropy source has failed its continuous health test.           |
| `KEY_SIZE_INVALID`     | Public key length does not match the declared scheme     | The key material is malformed                                                       |
| `NETWORK_MISMATCH`     | Signed message references a different network            | The message was signed for a different chain                                        |

***

## Python

```python
from cevex.exceptions import (
    CevexError,
    IdentityNotFoundError,
    IdentityRevokedError,
    SignatureInvalidError,
    NonceReplayError,
    RegistryUnavailableError,
    EntropyFailureError,
)

try:
    result = await verifier.verify(signed)
except IdentityRevokedError:
    print("Agent has been revoked")
except SignatureInvalidError:
    print("Signature verification failed")
except CevexError as e:
    print(f"CEVEX error: {e}")
```

***

## See Also

* [API Reference](/build/api-reference.md)
* [Quickstart](/build/quickstart.md)


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