---
title: ASE generated error messages for blocked requests
description: The API Security Enforcer (ASE) blocks certain requests based on application programming interface (API) Mapping or API Behavioral Security (ABS)-detected attacks. For these blocked requests, it sends a standard error message back to the client.
component: pingintelligence
version: 5.2
page_id: pingintelligence:pingintelligence_reference_guide:pingintelligence_ase_error_messages_blocked_requests
canonical_url: https://docs.pingidentity.com/pingintelligence/5.2/pingintelligence_reference_guide/pingintelligence_ase_error_messages_blocked_requests.html
revdate: June 4, 2024
---

# ASE generated error messages for blocked requests

The API Security Enforcer (ASE) blocks certain requests based on application programming interface (API) *(tooltip: \<div class="paragraph">
\<p>A specification of interactions available for building software to access an application or service.\</p>
\</div>)* Mapping or API Behavioral Security (ABS)-detected attacks. For these blocked requests, it sends a standard error message back to the client.

The following table describes the error messages.

| Blocked Connection  | HTTP Error Code | Error Definition    | Message Body             |
| ------------------- | --------------- | ------------------- | ------------------------ |
| Unknown API         | 503             | Service Unavailable | Error: Unknown API       |
| Unknown Hostname    | 503             | Service Unavailable | Error: Unknown Hostname  |
| Malformed Request   | 400             | Bad Request         | Error: Malformed Request |
| IP attack           | 403             | Unauthorized        | Error: Unauthorized      |
| Cookie attack       | 403             | Unauthorized        | Error: Unauthorized      |
| OAuth2 Token attack | 403             | Unauthorized        | Error: Unauthorized      |
| API Key attack      | 403             | Unauthorized        | Error: Unauthorized      |
| Username attack     | 403             | Unauthorized        | Error: Unauthorized      |

![Diagram of ASE returning a standard error message: 401 Unauthorized following bad request](../_images/czd1564008999697.png)