---
title: Common API errors and what they mean
description: Helps developers distinguish authentication, validation, recipient and internal errors.
---

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# Common API errors and what they mean

## Always start with the response code, response body and the current endpoint description at api.qvalia.io. Do not automatically repeat the same request until you know whether doing so could create a duplicate.

### Common error categories

| Error type | What to check |
| --- | --- |
| Authentication error | That the correct header is sent, the API key is active and it belongs to the correct environment. |
| Validation error or `Invalid payload` | Read the detailed message and check mandatory fields, data types, document type and Peppol rules. |
| Recipient or participant validation error | Check the complete Peppol ID and that the recipient is registered for the document type in the correct network. |
| Resource not found | Check the endpoint, HTTP method, URL version, account identifier and document ID against the current documentation. |
| Request too large | The complete API request may be up to 100 MB, including base64-encoded attachments. Reduce the request before trying again. |
| Internal Qvalia error | Save the timestamp, correlation ID and response body and contact support. |

### When the response is empty

Interpret an empty response according to the endpoint documentation. Check filters, date range, pagination and whether the document has already been read or retrieved before treating the response as an error.

### Troubleshooting information

Log the following without logging the API key or sensitive invoice content:

- date and time including time zone
- environment and base URL
- endpoint and HTTP method
- response code and response body
- `accountRegNo`
- correlation or transaction ID
- recipient's Peppol ID and document type when the error concerns delivery

### If it still does not work

- **Check once more:** the current API documentation, environment, method and complete error text.
- **Have this ready when contacting support:** the troubleshooting information above. Never send the API key.
- **Contact support:** through the support form at the bottom of https://qvalia.com or at help@qvalia.com.

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