What do HTTP status codes mean?
This article contains a compact list of HTTP status codes that you may encounter during an API call. What do these codes mean and what are the possible causes that result in the status code?
| HTTP | Description | Meaning |
| 2xx | Success | |
| 200 | Successful | Request successfully processed (may also return empty dataset) |
| 3xx | Redirection | |
| 302 | Temporarily moved | Resource temporarily moved (often due to incorrect headers) |
| 313 | Invalid file | The specified file is invalid or corrupt |
| 4xx | Client errors | |
| 400 | Invalid request | Invalid request: incorrect parameters, json, headers, API version or URL |
| 401 | Not logged in | Not authenticated: missing or invalid credentials or token |
| 403 | No access | No rights for this endpoint or service |
| 404 | Not found | Resource, endpoint or key not found |
| 405 | Method not allowed | HTTP method (GET/POST/PUT/DEL) not allowed for this resource |
| 415 | Unsupported format | Content type not supported (e.g., missing application/json) |
| 422 | Invalid input | Request correctly formed, but content invalid or validation messages |
| 423 | Locked | Resource is locked (record-lock) |
| 426 | Invalid configuration | Invalid document, collection, layout, setting, or file |
| 429 | Too many requests | Too many requests in a short time (rate limit exceeded) |
| 449 | Confirmation required | User interaction or confirmation is required to proceed |
| 455 | Add-on not available | Required add-on key is not available or not activated |
| 460 | Filename missing | Filename missing in the request |
| 496 | Invalid API key | API key missing or invalid |
| 497 | Action not allowed | Invalid action or MKG Exchange license is not active |
| 498 | Invalid session | Token expired/invalid or application unknown |
| 499 | Internal error (client) | Internal error on client or middleware side |
| 5xx | Server errors | |
| 500 | Server error | Unexpected server error (see _retVal codes) |
| 501 | Not implemented | Functionality is (yet) not implemented |
| 502 | Connection error | Bad gateway: issue between Tomcat and Progress |
| 503 | Unavailable | Service temporarily overloaded or under maintenance |
| 504 | Timeout | Gateway timeout: upstream server responds too slowly |
| _retVal | Meaning | |
| 4000 | Unknown error when calling MKG user | |
| 4010 | MKG user is not active | |
| 4020 | MKG user does not have a complex password | |
| 4030 | Session has expired | |
| 4050 | JSESSIONID is empty | |
| 7211 | Server terminated unexpectedly – incorrect request |
- Published:22 May 2026 14:43
- Latest update:22 May 2026 14:43
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