diff --git a/service/src/main/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseService.java b/service/src/main/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseService.java
index cad092342..83074a765 100644
--- a/service/src/main/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseService.java
+++ b/service/src/main/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseService.java
@@ -26,7 +26,6 @@ public String encodeToJson(IBaseResource resource) {
 
     private IParser prepareParser() {
         FhirContext ctx = FhirContext.forDstu3();
-        ctx.newJsonParser();
         ctx.setParserErrorHandler(new StrictErrorHandler());
         return ctx.newJsonParser();
     }
diff --git a/service/src/test/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseServiceTest.java b/service/src/test/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseServiceTest.java
index 4311b4b8d..785f97bc8 100644
--- a/service/src/test/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseServiceTest.java
+++ b/service/src/test/java/uk/nhs/adaptors/gp2gp/common/service/FhirParseServiceTest.java
@@ -44,6 +44,34 @@ void setUp() {
         fhirParseService = new FhirParseService();
     }
 
+    @Test
+    void shouldThrowValidationExceptionForInvalidJsonDiagnosticsField() {
+
+        String invalidJson = """
+                             {
+                             "resourceType": "OperationOutcome",
+                             "meta": {
+                                "profile": ["https://fhir.nhs.uk/STU3/StructureDefinition/GPConnect-OperationOutcome-1"]
+                             },
+                             "issue": [ {
+                                "severity": "error",
+                                "code": "value",
+                                "details": {
+                                    "coding": [ {
+                                        "system": "http://fhir.nhs.net/ValueSet/gpconnect-error-or-warning-code-1",
+                                        "code": "INVALID_IDENTIFIER_VALUE"
+                                    } ]
+                                },
+                                "diagnosticos": "Provide a conversationId that exists and retry the operation"
+                             } ]
+                             }
+                             """;
+
+        assertThrows(FhirValidationException.class, () -> {
+            fhirParseService.parseResource(invalidJson, OperationOutcome.class);
+        });
+    }
+
     @Test
     void ableToEncodeOperationOutcomeToJson() throws JsonProcessingException {