> For the complete documentation index, see [llms.txt](https://developers.mobile-text-alerts.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.mobile-text-alerts.com/getting-started/api-basics/error-response-codes.md).

# Error Response Codes

The Mobile Text API returns HTTP status codes and JSON-based error codes and messages.

## HTTP Status Codes

Each API request returns an HTTP status code. This three-digit code indicates the request outcome. See [Error Message Catalog](/getting-started/api-basics/error-response-codes/error-message-catalog.md) for detailed examples of errors you may encounter.

<table><thead><tr><th width="106">Code</th><th width="233"></th><th>Description</th></tr></thead><tbody><tr><td><mark style="color:green;"><code>200</code></mark></td><td><code>Success</code></td><td>Indicates a successful request and contains <a href="/getting-started/api-basics/request-response-headers.md#response-headers">response headers</a> with additional details about the request.</td></tr><tr><td><mark style="color:red;"><code>400</code></mark></td><td><code>BadRequestError</code></td><td>Indicates that the request was malformed or invalid. Make sure you included all required fields for the endpoint in the request.</td></tr><tr><td><mark style="color:red;"><code>401</code></mark></td><td><code>UnauthorizedError</code></td><td>Indicates that the client is not authorized to access the requested resource. Make sure you include a valid <a href="/getting-started/get-an-api-key.md#bearer-token-authentication">API key</a> in the request header.</td></tr><tr><td><mark style="color:red;"><code>403</code></mark></td><td><code>ForbiddenError</code></td><td>Indicates the client is authenticated but not authorized to access the requested resource.</td></tr><tr><td><mark style="color:red;"><code>429</code></mark></td><td><code>RateLimitError</code></td><td>Indicates too many requests to the server within a window of time, exceeding the allowed <a href="/getting-started/api-basics/rate-limits.md">rate limit</a> for that endpoint.</td></tr><tr><td><mark style="color:red;"><code>500</code></mark></td><td><code>InternalServerError</code></td><td>Indicates the server encountered an unexpected error that prevented it from fulfilling the request. This usually means there is an issue with the server, not the request.</td></tr></tbody></table>


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