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HttpClientStreamableHttpTransport: handle HTTP 405 #900

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Merged
Kehrlann merged 1 commit into from
Apr 2, 2026
Merged

HttpClientStreamableHttpTransport: handle HTTP 405 #900

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8 changes: 4 additions & 4 deletions ...main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
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Original file line number Diff line number Diff line change
Expand Up @@ -298,6 +298,10 @@ private Mono<Disposable> reconnect(McpTransportStream<Disposable> stream) {
"Authorization error connecting to SSE stream",
responseEvent.responseInfo()));
}
else if (statusCode == METHOD_NOT_ALLOWED) {
logger.debug("The server does not support SSE streams, using request-response mode.");
return Flux.empty();
}

if (!(responseEvent instanceof ResponseSubscribers.SseResponseEvent sseResponseEvent)) {
return Flux.<McpSchema.JSONRPCMessage>error(new McpTransportException(
Expand Down Expand Up @@ -344,10 +348,6 @@ else if (statusCode >= 200 && statusCode < 300) {
return Flux.empty();
}
}
else if (statusCode == METHOD_NOT_ALLOWED) { // NotAllowed
logger.debug("The server does not support SSE streams, using request-response mode.");
return Flux.empty();
}
else if (statusCode == NOT_FOUND) {

if (transportSession != null && transportSession.sessionId().isPresent()) {
Expand Down
22 changes: 21 additions & 1 deletion ...lcontextprotocol/client/transport/HttpClientStreamableHttpTransportErrorHandlingTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
import com.sun.net.httpserver.HttpServer;
import io.modelcontextprotocol.client.transport.customizer.McpHttpClientAuthorizationErrorHandler;
import io.modelcontextprotocol.common.McpTransportContext;
import org.reactivestreams.Publisher;
import io.modelcontextprotocol.server.transport.TomcatTestUtil;
import io.modelcontextprotocol.spec.HttpHeaders;
import io.modelcontextprotocol.spec.McpClientTransport;
Expand All @@ -34,6 +33,7 @@
import org.junit.jupiter.api.Timeout;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Mono;
import reactor.test.StepVerifier;

Expand Down Expand Up @@ -369,6 +369,26 @@ else if (status == 404) {
StepVerifier.create(transport.closeGracefully()).verifyComplete();
}

@Test
void test405OnConnectReturnsEmptyFlux() {
serverSseResponseStatus.set(405);
AtomicReference<Throwable> capturedException = new AtomicReference<>();
var transport = HttpClientStreamableHttpTransport.builder(HOST).openConnectionOnStartup(true).build();
transport.setExceptionHandler(capturedException::set);

var messages = new ArrayList<McpSchema.JSONRPCMessage>();
StepVerifier.create(transport.connect(msg -> msg.doOnNext(messages::add))).verifyComplete();

Awaitility.await()
.atMost(Duration.ofSeconds(1))
.untilAsserted(() -> assertThat(processedSseConnectCount.get()).isEqualTo(1));

assertThat(messages).isEmpty();
assertThat(capturedException.get()).isNull();

StepVerifier.create(transport.closeGracefully()).verifyComplete();
}

@Nested
class AuthorizationError {

Expand Down
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