Details of the common error handling pattern(s) across the GP Connect API

As a nationally brokered FHIR® API, the GP Connect error handling approach defined below closely follows the approach of the Spine Core FHIR API Framework.

However, the guidance given below is the definitive error handling definition for the GP Connect API and thus the Spine Core error handling guidance should be viewed for context only.

Operation outcome usage

In the event of an error, provider systems SHALL respond by providing an OperationOutcome resource profiled to GPConnect-OperationOutcome-1.

The GPConnect-OperationOutcome-1:

  • SHALL contain a definition of severity in the OperationOutcome.issue.severity field providing a value from the valueset-issue-severity value set. In all cases described in this guidance, the value used will be error.
  • SHALL contain a definition of the type of error in the OperationOutcome.issue.code element, providing a value from the issue-type value set.
  • SHALL contain details of the Spine error code in the OperationOutcome.issue.details.coding.code and OperationOutcome.issue.details.coding.display fields. These shall be taken from the standard set of NHS Spine error codes as defined in the spine-error-or-warning-code-1 value set. The Spine error and warning codes provide a greater degree of error handling granularity, and also ensure a standardised error handling approach across NHS APIs.
  • SHOULD provide additional diagnostic details of the error in the OperationOutcome.diagnostics property where such details securely provide additional error context for consumer applications.

The sections below provide guidance on the error details to be returned in a number of key scenarios.

Identity validation errors

Provider systems SHALL respond by returning one of the following OperationOutcome error codes where FHIR resource identity error scenarios are encountered:

HTTP code Issue type Spine error code - code Spine error code - display
400 value INVALID_IDENTIFIER_SYSTEM Invalid identifier system
400 value INVALID_IDENTIFIER_VALUE Invalid identifier value
400 value INVALID_NHS_NUMBER NHS number invalid
400 business-rule INVALID_PATIENT_DEMOGRAPHICS Invalid patient demographics (that is, PDS trace failed)
404 not-found ORGANISATION_NOT_FOUND Organisation record not found
404 not-found PATIENT_NOT_FOUND Patient record not found
404 not-found PRACTITIONER_NOT_FOUND Practitioner record not found
404 not-found NO_RECORD_FOUND No record found

Example: Invalid NHS number supplied

If an invalid NHS number value is supplied to the $gpc.getcarerecord operation, the following error details would be returned:

{
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "value",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "INVALID_NHS_NUMBER",
				"display": "Invalid NHS number"
			}]
		}
	}]
}

Example: Patient not found

For example, if a valid NHS number value is supplied to the $gpc.getcarerecord operation but no GP record exists for that patient, then the following error details would be returned:

{
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "not-found",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "PATIENT_NOT_FOUND",
				"display": "Patient not found"
			}]
		}
	}]
}

Example: Resource not found

This is a catch-all where a request for a resource instance cannot be found at the FHIR server, where more specific Spine error codes (such as PATIENT_NOT_FOUND) cannot be used.

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "not-found",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "NO_RECORD_FOUND",
				"display": "No record found"
			}]
		}
	}]
}

Security validation errors

When responding to consumer API requests, provider systems SHALL return one of the following OperationOutcome details when enforcement of local consent rules result in an error condition:

HTTP code Issue type Spine error code - code Spine error code - display
403 forbidden NO_PATIENT_CONSENT Patient has not provided consent to share data
403 forbidden NO_ORGANISATION_CONSENT Organisation has not provided consent to share data
403 forbidden ACCESS_DENIED Access denied

For example, if the patient has requested that their record should not be shared then the following error details would be returned:

{
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "forbidden",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "NO_PATIENT_CONSENT",
				"display": "Patient has not provided consent to share data" 
			}]
		}
	}]
}

Duplicate errors

When responding to consumer API requests, provider systems SHALL return one of the following OperationOutcome details when a resource could not be created or updated because it would cause a duplicate in the provider system:

HTTP code Issue type Spine error code - code Spine error code - display
409 duplicate DUPLICATE_REJECTED Create would lead to creation of a duplicate resource

Example: Attempting to register a patient that already exists

For example, if the consumer attempted to register a patient that already has an active record on the provider system the error details would be returned:

{
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "duplicate",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "DUPLICATE_REJECTED",
				"display": "Create would lead to creation of duplicate resource" 
			}]
		}
	}]
}

Resource validation errors

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

HTTP code Issue type Spine error code - code Spine error code - display
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_PARAMETER would be used in the following, or similar, scenarios:

  • Unexpected parameter value for a custom operation. For example, a lowercase value is supplied to the recordSection parameter of the $gpc.getcarerecord operation.
  • An invalid date/time value specified in a custom operation parameter. For example, an invalid timePeriod defined in the timePeriod input parameter to the $gpc.getcarerecord operation.

INVALID_RESOURCE would be used in situations such as the following:

  • Resource fails to validate against StructureDefinition (either in request body or in JSON Web Tokens (JWT) claim).
  • A resource fails to be processed 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, when using the ‘Book an appointment’ API use case, a consumer includes a reference to a slot which does not exist at the server. The following error details would be returned:

{
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "invalid",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "REFERENCE_NOT_FOUND",
				"display": "FHIR reference not found"
			}]
		},
	    "diagnostics": "Reference to Slot/6 - no such slot exists at the server"
		"location": "/f:Slot/f:6"
	}]
}

Malformed request errors

When the server cannot or will not process a request due to an apparent client error then the following BAD_REQUEST error SHALL be used to return debug details.

HTTP code Issue type Spine error code - code Spine error code - display
400 invalid BAD_REQUEST Submitted request is malformed/invalid.

BAD_REQUEST Spine error codes should be used in the following types of scenario:

  • JWT claims information is not valid JSON, is null, or has an invalid value
  • invalid FHIR resource in JWT claim (for example, patient resource when practitioner expected)
  • malformed JSON or XML content in request body
  • an expected header (for example, interaction ID header) is missing or invalid
  • invalid HTTP verb used (for example, using POST to read a patient)
  • InteractionID header does not match request

Example: Malformed JSON claim in request

For example, if the request contained a null aud claim in the JWT, then the following error details would be returned:

 {
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "invalid",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "BAD_REQUEST",
				"display": "Bad request"
			}]
		},
		"diagnostics": "Empty JWT aud claim"
	}]
}

Internal server errors

When the FHIR server has received a request for an operation or FHIR resource which is not (yet) implemented, then the NOT_IMPLEMENTED Spine error code SHALL be used.

HTTP code Issue type Spine error code - code Spine error code - display
501 not-supported NOT_IMPLEMENTED FHIR resource or operation not implemented at server

When the error is unexpected and the server can’t be more specific on the exact nature of the problem then the INTERNAL_SERVER_ERROR Spine error code SHALL be used, and diagnostics SHALL be included to provide detail of the error.

HTTP code Issue type Spine error code - code Spine error code - display
500 processing INTERNAL_SERVER_ERROR Unexpected internal server error.

Example: Unexpected exception

For example, if an unexpected internal exception is thrown by either an Operation or RESTful API, then the following error details would be returned:

 {
	"resourceType": "OperationOutcome",
	"meta": {
		"profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
	},
	"issue": [{
		"severity": "error",
		"code": "exception",
		"details": {
			"coding": [{
				"system": "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1",
				"code": "INTERNAL_SERVER_ERROR",
				"display": "Internal server error"
			}]
		},
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}

Spine Secure Proxy (SSP) errors

When the Spine Secure Proxy cannot or will not process a request then one of the following errors SHALL be used to return debug details:

HTTP code Issue type Description of error
403 forbidden The sender or receiver’s ASID is not authorised for this interaction.
405 not-supported Bad request for an unsupported HTTP verb such as TRACE.
415 not-supported A consumer application asked for an unsupported media type.
502 transient A downstream server is offline.
504 transient A downstream server timed out.

SSP error example: ASID check failed

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "forbidden",
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}

SSP error example: method not allowed

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "not-supported",
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}

SSP error example: unsupported media type

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "not-supported",
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}

SSP error example: bad gateway

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "transient",
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}

SSP error example: gateway timeout

{
	"resourceType": "OperationOutcome",
	"issue": [{
		"severity": "error",
		"code": "transient",
		"diagnostics": "Any further internal debug details i.e. stack trace details etc."
	}]
}