diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
index 853aed2bf..648e8b3ea 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
@@ -326,8 +326,10 @@ else if (mediaType.isCompatibleWith(MediaType.APPLICATION_JSON)) {
 						}
 					}
 					else {
-						if (isNotFound(response) && !sessionRepresentation.equals(MISSING_SESSION_ID)) {
-							return mcpSessionNotFoundError(sessionRepresentation);
+						if (isNotFound(response)) {
+							if (transportSession.sessionId().isPresent()) {
+								return mcpSessionNotFoundError(sessionRepresentation);
+							}
 						}
 						return this.extractError(response, sessionRepresentation);
 					}