> ## Documentation Index > Fetch the complete documentation index at: https://docs.landing.ai/llms.txt > Use this file to discover all available pages before exploring further. # Troubleshoot Classification > Resolve Classify API errors using status codes, causes, and recommended fixes. Use this section to troubleshoot issues encountered when calling the [Classify API](https://docs.landing.ai/dpt3/classify.md) (`/v1/ade/classify`). ## Common Status Codes | Status Code | Name | Description | What to Do | | - | - | - | - | | 200 | Success | Classification completed successfully. | Continue with normal operations. | | 400 | Bad Request | The document URL could not be fetched, or the model version is unknown. | Review the error message. See [Status 400](#status-400-bad-request). | | 401 | Unauthorized | Missing or invalid API key. | Check that your API key header is present and contains a valid [API key](https://docs.landing.ai/dpt3/agentic-api-key.md). | | 402 | Payment Required | Your account does not have enough credits to complete processing. | If you have multiple accounts, make sure you're using the correct [API key](https://docs.landing.ai/dpt3/agentic-api-key.md). Add more credits to your account. | | 413 | Content Too Large | The document exceeds the 50 MiB size limit. | Reduce the file size and retry. See [Status 413](#status-413-content-too-large). | | 422 | Unprocessable Entity | Input validation failed, or the document could not be read or converted. | Review your request parameters. See [Status 422](#status-422-unprocessable-entity). | | 429 | Too Many Requests | Rate limit exceeded. | Wait before retrying. Reduce request frequency and implement exponential backoff. | | 500 | Internal Server Error | Server error during classification. | Retry. If the issue persists, contact [support@landing.ai](mailto:support@landing.ai). See [Status 500](#status-500-internal-server-error). | | 502 | Bad Gateway | The classification service returned an error. | Retry. If the issue persists, contact [support@landing.ai](mailto:support@landing.ai). See [Status 502](#status-502-bad-gateway). | | 504 | Gateway Timeout | Request processing exceeded the timeout limit. | Reduce document size or number of pages. See [Status 504](#status-504-gateway-timeout). | ## Status 400: Bad Request This status code indicates invalid request parameters or client-side errors. Review the specific error message to identify the issue. ### Error: Invalid document URL This error occurs when the URL provided in `document_url` cannot be fetched. The URL may be invalid, unreachable, or return a non-200 response. **What to do:** * Verify the URL is correct and publicly accessible. * Confirm the server hosting the document does not require authentication or block external requests. * If the document is behind a firewall or requires credentials, download it locally and upload it using the `document` parameter instead. ### Error: Unknown model version This error occurs when the `model` parameter names a version that does not exist. The error message lists the available versions. **What to do:** * Omit `model` to use the latest version, or pass one of the versions the error message lists. ## Status 413: Content Too Large This error occurs when the document you submit exceeds the 50 MiB file size limit. **What to do:** * Reduce the file size before uploading. * If the document is a PDF, consider compressing it or splitting it into smaller files before classifying. ## Status 422: Unprocessable Entity This status code indicates input validation failures. Review the error message and adjust your request parameters. ### Error: Document could not be converted This error occurs when a document in a supported Office format (such as DOCX or PPTX) could not be converted to PDF for processing. The file may be corrupted or encrypted. **What to do:** * Convert the document to PDF before uploading and retry. * If the error persists, contact [support@landing.ai](mailto:support@landing.ai). ### Error: Unsupported file format This error occurs when you submit a file type that the Classify API does not support, such as a spreadsheet (XLSX or CSV). **What to do:** * Convert your document to a supported format before calling the API. * For supported file formats, see [Supported File Types](https://docs.landing.ai/dpt3/classify.md#supported-file-types). ### Error: Both document fields provided This error occurs when you include both `document` and `document_url` in the same request. **What to do:** * Include only one document input per request: either upload a file using `document` or provide a URL using `document_url`. ## Status 500: Internal Server Error This error indicates an unexpected server error occurred during classification. **What to do:** * Retry the request. * If the error persists, contact [support@landing.ai](mailto:support@landing.ai). ## Status 502: Bad Gateway This error occurs when the internal classification service fails to process the document, typically due to a transient error in the large language model (LLM) service. **What to do:** * Retry the request. * If the error persists, contact [support@landing.ai](mailto:support@landing.ai). ## Status 504: Gateway Timeout This error occurs when classification does not finish within the 475-second limit for synchronous requests. **What to do:** * Reduce the size of your document or the number of pages being classified. * If the error persists, contact [support@landing.ai](mailto:support@landing.ai). ## When Are Credits Consumed? Credits are consumed only when the Classify API returns a 200 status code. All other responses, including errors, do not consume credits. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.