What are the API error codes?

Below is a list of error codes generated by the DataCite APIs and few hints to help with debugging.

Common Issues

Wrong endpoint - check if the endpoint is for test or production
Bad credentials - always use a repository account to register DOIs
Incorrectly formatted metadata - (see DataCite Metadata Schema for required fields and API reference for fields supported in JSON

Error code	Message	Possible Solution
400	Bad Request	Check the docs again and try to reproduce.
401	Bad credentials.	Unauthorized - Check your password.
403	You are not authorized to access this resource.	Forbidden - Check your password or validate that you are updating a DOI/prefix/repository you have permissions for.
404	The resource you are looking for doesn't exist.	Not Found - The resource is not found e.g. fetching a DOI/Repository/Member details. May also indicate an issue with credentials. Check your username and password.
405	Method Not Allowed	The http method on the request made is not supported. Check documentation.
422	Unprocessable Entity	Check the contents of your request, the system understood but it was unable to process it. For a DOI update this might be invalid URL or metadata is invalid.
409	The resource already exists	Check whether the DOI has already been registered: https://api.datacite.org/dois/YOURDOINAME
500	Internal Server Error	Try to reproduce and report steps that caused it.
502	Bad Gateway	Most likely a temporary issue, try again
503	Service Unavailable	Check our status page status.datacite.org.
504	Gateway Timeout	Check our status page/releases status.datacite.org.