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fix: use application/json Content-Type for HTTP+JSON error responses #769

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Merged
ehsavoie merged 3 commits into from
Mar 30, 2026
Merged

fix: use application/json Content-Type for HTTP+JSON error responses #769

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944f6b5
fix: use application/json Content-Type for HTTP+JSON error responses
jmesnil Mar 25, 2026
85fc370
refactor: Use APPLICATION_JSON constant in the tests
jmesnil Mar 25, 2026
4a81b74
Merge branch 'main' into 768_application_json_for_errors
jmesnil Mar 27, 2026
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3 changes: 1 addition & 2 deletions common/src/main/java/io/a2a/common/MediaType.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,5 @@

public interface MediaType {

public static final String APPLICATION_JSON = "application/json";
public static final String APPLICATION_PROBLEM_JSON = "application/problem+json";
String APPLICATION_JSON = "application/json";
}
7 changes: 3 additions & 4 deletions reference/jsonrpc/src/main/java/io/a2a/server/apps/quarkus/A2AServerRoutes.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
package io.a2a.server.apps.quarkus;

import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.server.ServerCallContext.TRANSPORT_KEY;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.HEADERS_KEY;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.METHOD_NAME_KEY;
Expand Down Expand Up @@ -248,7 +247,7 @@ public class A2AServerRoutes {
*
* <p><b>Processing Flow:</b>
* <ol>
* <li>Parse JSON-RPC request body using {@link JSONRPCUtils#parseRequestBody}</li>
* <li>Parse JSON-RPC request body using {@link JSONRPCUtils#parseRequestBody(String, String)}</li>
* <li>Create {@link ServerCallContext} from routing context</li>
* <li>Route to streaming or non-streaming handler</li>
* <li>Handle errors with appropriate JSON-RPC error codes</li>
Expand Down Expand Up @@ -297,7 +296,7 @@ public void invokeJSONRPCHandler(@Body String body, RoutingContext rc) {
if (error != null) {
rc.response()
.setStatusCode(200)
.putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON)
.putHeader(CONTENT_TYPE, APPLICATION_JSON)
.end(serializeResponse(error));
} else if (streaming) {
final Multi<? extends A2AResponse<?>> finalStreamingResponse = streamingResponse;
Expand All @@ -313,7 +312,7 @@ public void invokeJSONRPCHandler(@Body String body, RoutingContext rc) {
} else {
rc.response()
.setStatusCode(200)
.putHeader(CONTENT_TYPE, nonStreamingResponse.getError() != null ? APPLICATION_PROBLEM_JSON : APPLICATION_JSON)
.putHeader(CONTENT_TYPE, APPLICATION_JSON)
.end(serializeResponse(nonStreamingResponse));
}
}
Expand Down
9 changes: 4 additions & 5 deletions reference/jsonrpc/src/test/java/io/a2a/server/apps/quarkus/A2AServerRoutesTest.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
package io.a2a.server.apps.quarkus;

import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.spec.A2AMethods.DELETE_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
Expand Down Expand Up @@ -718,7 +717,7 @@ public void testTenantExtraction_StreamingRequest() {
}

@Test
public void testJsonParseError_ContentTypeIsProblemJson() {
public void testJsonParseError_ContentTypeIsApplicationJson() {
// Arrange - invalid JSON
String invalidJson = "not valid json {{{";
when(mockRequestBody.asString()).thenReturn(invalidJson);
Expand All @@ -727,11 +726,11 @@ public void testJsonParseError_ContentTypeIsProblemJson() {
routes.invokeJSONRPCHandler(invalidJson, mockRoutingContext);

// Assert
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON);
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
public void testMethodNotFound_ContentTypeIsProblemJson() {
public void testMethodNotFound_ContentTypeIsApplicationJson() {
// Arrange - unknown method
String jsonRpcRequest = """
{
Expand All @@ -746,7 +745,7 @@ public void testMethodNotFound_ContentTypeIsProblemJson() {
routes.invokeJSONRPCHandler(jsonRpcRequest, mockRoutingContext);

// Assert
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON);
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

/**
Expand Down
39 changes: 20 additions & 19 deletions reference/rest/src/test/java/io/a2a/server/rest/quarkus/A2AServerRoutesTest.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
package io.a2a.server.rest.quarkus;

import static io.a2a.common.MediaType.APPLICATION_JSON;
import static io.a2a.spec.A2AMethods.CANCEL_TASK_METHOD;
import static io.a2a.spec.A2AMethods.DELETE_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_METHOD;
Expand Down Expand Up @@ -82,7 +83,7 @@ public void setUp() {
when(mockRoutingContext.user()).thenReturn(null);
when(mockRequest.headers()).thenReturn(mockHeaders);
when(mockRequest.params()).thenReturn(mockParams);
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn("application/json");
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn(APPLICATION_JSON);
when(mockRoutingContext.body()).thenReturn(mockRequestBody);
when(mockRequestBody.asString()).thenReturn("{}");
when(mockResponse.setStatusCode(any(Integer.class))).thenReturn(mockResponse);
Expand All @@ -96,7 +97,7 @@ public void testSendMessage_MethodNameSetInContext() {
// Arrange
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.sendMessage(any(ServerCallContext.class), anyString(), anyString())).thenReturn(mockHttpResponse);

Expand All @@ -117,7 +118,7 @@ public void testSendMessageStreaming_MethodNameSetInContext() {
// Arrange
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.sendStreamingMessage(any(ServerCallContext.class), anyString(), anyString()))
.thenReturn(mockHttpResponse);
Expand All @@ -140,7 +141,7 @@ public void testGetTask_MethodNameSetInContext() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task123");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{test:value}");
when(mockRestHandler.getTask(any(ServerCallContext.class), anyString(), anyString(), any())).thenReturn(mockHttpResponse);

Expand All @@ -162,7 +163,7 @@ public void testCancelTask_MethodNameSetInContext() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task123");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.cancelTask(any(ServerCallContext.class), anyString(), anyString(), anyString())).thenReturn(mockHttpResponse);

Expand All @@ -184,7 +185,7 @@ public void testCancelTask_WithMetadata() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task456");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{\"id\":\"task456\",\"status\":\"cancelled\"}");

String requestBody = """
Expand Down Expand Up @@ -217,7 +218,7 @@ public void testCancelTask_WithEmptyMetadata() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task789");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{\"id\":\"task789\"}");

String requestBody = """
Expand Down Expand Up @@ -246,7 +247,7 @@ public void testCancelTask_WithNoMetadataField() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task999");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{\"id\":\"task999\"}");

String requestBody = "{}";
Expand All @@ -271,7 +272,7 @@ public void testCancelTask_WithNullBody() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task111");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{\"id\":\"task111\"}");

ArgumentCaptor<String> bodyCaptor = ArgumentCaptor.forClass(String.class);
Expand All @@ -293,7 +294,7 @@ public void testCancelTask_WithComplexMetadata() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task222");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{\"id\":\"task222\"}");

String requestBody = """
Expand Down Expand Up @@ -331,7 +332,7 @@ public void testSubscribeTask_MethodNameSetInContext() {
when(mockRoutingContext.pathParam("taskId")).thenReturn("task123");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.subscribeToTask(any(ServerCallContext.class), anyString(), anyString()))
.thenReturn(mockHttpResponse);
Expand All @@ -354,7 +355,7 @@ public void testCreateTaskPushNotificationConfiguration_MethodNameSetInContext()
when(mockRoutingContext.pathParam("taskId")).thenReturn("task123");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.createTaskPushNotificationConfiguration(any(ServerCallContext.class), anyString(), anyString(), anyString())).thenReturn(mockHttpResponse);

Expand All @@ -377,7 +378,7 @@ public void testGetTaskPushNotificationConfiguration_MethodNameSetInContext() {
when(mockRoutingContext.pathParam("configId")).thenReturn("config456");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.getTaskPushNotificationConfiguration(any(ServerCallContext.class), anyString(), anyString(), anyString())).thenReturn(mockHttpResponse);

Expand All @@ -400,7 +401,7 @@ public void testListTaskPushNotificationConfigurations_MethodNameSetInContext()
when(mockRoutingContext.pathParam("taskId")).thenReturn("task123");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.listTaskPushNotificationConfigurations(any(ServerCallContext.class), anyString(), anyString(), anyInt(), anyString()))
.thenReturn(mockHttpResponse);
Expand All @@ -424,7 +425,7 @@ public void testDeleteTaskPushNotificationConfiguration_MethodNameSetInContext()
when(mockRoutingContext.pathParam("configId")).thenReturn("config456");
HTTPRestResponse mockHttpResponse = mock(HTTPRestResponse.class);
when(mockHttpResponse.getStatusCode()).thenReturn(200);
when(mockHttpResponse.getContentType()).thenReturn("application/json");
when(mockHttpResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockHttpResponse.getBody()).thenReturn("{}");
when(mockRestHandler.deleteTaskPushNotificationConfiguration(any(ServerCallContext.class), anyString(), anyString(), anyString())).thenReturn(mockHttpResponse);

Expand All @@ -446,7 +447,7 @@ public void testSendMessage_UnsupportedContentType_ReturnsContentTypeNotSupporte
// Arrange
HTTPRestResponse mockErrorResponse = mock(HTTPRestResponse.class);
when(mockErrorResponse.getStatusCode()).thenReturn(415);
when(mockErrorResponse.getContentType()).thenReturn("application/problem+json");
when(mockErrorResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockErrorResponse.getBody()).thenReturn("{\"error\":{\"code\":415,\"status\":\"INVALID_ARGUMENT\",\"message\":\"Incompatible content types\",\"details\":[{\"reason\":\"CONTENT_TYPE_NOT_SUPPORTED\",\"domain\":\"a2a-protocol.org\"}]}}");
when(mockRestHandler.createErrorResponse(any(ContentTypeNotSupportedError.class))).thenReturn(mockErrorResponse);
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn("text/plain");
Expand All @@ -464,7 +465,7 @@ public void testSendMessageStreaming_UnsupportedContentType_ReturnsContentTypeNo
// Arrange
HTTPRestResponse mockErrorResponse = mock(HTTPRestResponse.class);
when(mockErrorResponse.getStatusCode()).thenReturn(415);
when(mockErrorResponse.getContentType()).thenReturn("application/problem+json");
when(mockErrorResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockErrorResponse.getBody()).thenReturn("{\"error\":{\"code\":415,\"status\":\"INVALID_ARGUMENT\",\"message\":\"Incompatible content types\",\"details\":[{\"reason\":\"CONTENT_TYPE_NOT_SUPPORTED\",\"domain\":\"a2a-protocol.org\"}]}}");
when(mockRestHandler.createErrorResponse(any(ContentTypeNotSupportedError.class))).thenReturn(mockErrorResponse);
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn("text/plain");
Expand All @@ -482,9 +483,9 @@ public void testSendMessage_UnsupportedProtocolVersion_ReturnsVersionNotSupporte
// Arrange: content type is OK, but RestHandler returns a VersionNotSupportedError response
HTTPRestResponse mockErrorResponse = mock(HTTPRestResponse.class);
when(mockErrorResponse.getStatusCode()).thenReturn(400);
when(mockErrorResponse.getContentType()).thenReturn("application/problem+json");
when(mockErrorResponse.getContentType()).thenReturn(APPLICATION_JSON);
when(mockErrorResponse.getBody()).thenReturn("{\"error\":{\"code\":400,\"status\":\"UNIMPLEMENTED\",\"message\":\"Protocol version not supported\",\"details\":[{\"reason\":\"VERSION_NOT_SUPPORTED\",\"domain\":\"a2a-protocol.org\"}]}}");
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn("application/json");
when(mockRequest.getHeader(any(CharSequence.class))).thenReturn(APPLICATION_JSON);
when(mockRestHandler.sendMessage(any(ServerCallContext.class), anyString(), anyString()))
.thenReturn(mockErrorResponse);

Expand Down
3 changes: 1 addition & 2 deletions transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
package io.a2a.transport.rest.handler;

import static io.a2a.common.MediaType.APPLICATION_JSON;
import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.server.util.async.AsyncUtils.createTubeConfig;

import io.a2a.spec.A2AErrorCodes;
Expand Down Expand Up @@ -683,7 +682,7 @@ public HTTPRestResponse createErrorResponse(A2AError error) {

private HTTPRestResponse createErrorResponse(int statusCode, A2AError error) {
String jsonBody = new HTTPRestErrorResponse(error).toJson();
return new HTTPRestResponse(statusCode, APPLICATION_PROBLEM_JSON, jsonBody);
return new HTTPRestResponse(statusCode, APPLICATION_JSON, jsonBody);
}

private HTTPRestStreamingResponse createStreamingResponse(Flow.Publisher<StreamingEventKind> publisher) {
Expand Down
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