Common Error Codes

Caution

This page is a stub. A catalogue of common error codes — particularly domain-specific codes that appear inside the errors array — will be added here.

HTTP status codes

The eFiling API uses standard HTTP status codes:

Status	Meaning	What to do
200	OK	Request succeeded.
400	Bad Request	Fix the request shape / parameters.
401	Unauthorized	Check your API key and Authorization header.
403	Forbidden	The key is valid but lacks access.
404	Not Found	Check the resource ID.
429	Too Many Requests	Back off — see Rate limiting.
500	Internal Server Error	Retry with backoff; contact support if persistent.
503	Service Unavailable	Retry with backoff.

Domain error codes

Caution

The list of domain-specific error codes that can appear in the errors array of a response body (e.g. validation failures, Companies House rejection reasons) will be added here.