OperationOutcome resource (FHIR R4)

OperationOutcome is the FHIR R4 resource for a collection of error, warning, or information messages that result from a system action.

Resource	OperationOutcome
FHIR version	R4 (4.0.1)
Canonical URL	http://hl7.org/fhir/StructureDefinition/OperationOutcome
Required elements	issue (1..*)

Example

{
  "resourceType": "OperationOutcome",
  "id": "operationoutcome-b97451baa826d70f971609ae3dfb317f",
  "issue": [
    {
      "severity": "fatal",
      "code": "invalid"
    }
  ]
}

Generated by the Pidgeon engine: pidgeon generate OperationOutcome --seed 20260722.

Validation context

strict pidgeon validate grades a OperationOutcome instance against the base R4 structure definition: missing required elements raise REQUIRED_FIELD_MISSING and cardinality violations raise CARDINALITY_MIN or CARDINALITY_MAX.(REQUIRED_FIELD_MISSING)

This answer, in your terminal

pidgeon lookup OperationOutcome

Wire it into your AI agent:

claude mcp add pidgeon -- npx -y @pidgeonhealth/mcp

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