Implementation guide for interoperable medicines

This guidance is under active development by NHS England and content may be added or updated on a regular basis.

Resource validation errors

Where FHIR resource validation issues arise during processing of consumer requests, provider systems MUST utilise one the following error details:

HTTP code Issue type Error code Error message
422 invalid INVALID_RESOURCE Submitted resource is not valid.
422 invalid INVALID_PARAMETER Submitted parameter is not valid.
422 invalid REFERENCE_NOT_FOUND Referenced resource not found.

Detailed diagnostic information MUST be supplied when erroring on the codes above.

INVALID_PARAMATER would be used in the following, or similar, scenarios:

  • An invalid date / time value specified in a custom operation parameter.

INVALID_RESOURCE would be used in situations such as the following:

  • The resource failed structural validation
  • A resource failed to be procesed because of a FHIR constraint, or other rule application, where the error is not already covered by other error codes

REFERENCE_NOT_FOUND describes a scenario where a consumer POSTs a FHIR resource which contains a FHIR reference that cannot be found.

Example: Reference not found

For example, if a MedicationRequest referenced a Practitioner resource that could not be found or resolved by the server. The following error details would be returned:

    "resourceType": "OperationOutcome",
    "meta": {
        "profile": [
    "issue": [
            "severity": "error",
            "code": "invalid",
            "details": {
                "coding": [
                        "system": "",
                        "code": "REFERENCE_NOT_FOUND",
                        "display": "FHIR reference not found"
            "diagnostics": "Referenced Practitioner resource not found"

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