diff --git a/plugins/golang-filter/mcp-session/filter.go b/plugins/golang-filter/mcp-session/filter.go
index 9d9a27605..f31fa2404 100644
--- a/plugins/golang-filter/mcp-session/filter.go
+++ b/plugins/golang-filter/mcp-session/filter.go
@@ -289,8 +289,18 @@ func (f *filter) encodeDataFromRestUpstream(buffer api.BufferInstance, endStream
 func (f *filter) encodeDataFromSSEUpstream(buffer api.BufferInstance, endStream bool) api.StatusType {
 	bufferBytes := buffer.Bytes()
 	bufferData := string(bufferBytes)
+	api.LogDebugf("Received SSE data: %q, length: %d, endStream: %v", bufferData, len(bufferData), endStream)
 
-	err, endpointUrl := f.findEndpointUrl(bufferData)
+	// Combine cached data with new data
+	var combinedData string
+	if len(f.cachedResponseBody) > 0 {
+		combinedData = string(f.cachedResponseBody) + bufferData
+		api.LogDebugf("Combined with cached data: %q, total length: %d", combinedData, len(combinedData))
+	} else {
+		combinedData = bufferData
+	}
+
+	err, endpointUrl := f.findEndpointUrl(combinedData)
 	if err != nil {
 		api.LogWarnf("Failed to find endpoint URL in SSE data: %v", err)
 		f.needProcess = false
@@ -298,8 +308,12 @@ func (f *filter) encodeDataFromSSEUpstream(buffer api.BufferInstance, endStream
 	}
 	if endpointUrl == "" {
 		// No endpoint URL found. Need to buffer and check again.
-		return api.StopAndBuffer
+		f.cachedResponseBody = []byte(combinedData)
+		buffer.Reset()
+		return api.Continue
 	}
+	// Clear cached data
+	f.cachedResponseBody = nil
 
 	// Remove query string since we don't need to change it.
 	queryStringIndex := strings.IndexAny(endpointUrl, "?")
@@ -310,12 +324,12 @@ func (f *filter) encodeDataFromSSEUpstream(buffer api.BufferInstance, endStream
 	if changed, newEndpointUrl := f.rewriteEndpointUrl(endpointUrl); changed {
 		api.LogDebugf("The endpoint URL is changed.\n  Old: %s\n  New: %s", endpointUrl, newEndpointUrl)
 
-		endpointUrlIndex := strings.Index(bufferData, endpointUrl)
+		endpointUrlIndex := strings.Index(combinedData, endpointUrl)
 		if endpointUrlIndex == -1 {
 			api.LogWarnf("Something wrong, the previously found endpoint URL %s not found in the SSE data now", endpointUrl)
 		} else {
-			bufferData = bufferData[:endpointUrlIndex] + newEndpointUrl + bufferData[endpointUrlIndex+len(endpointUrl):]
-			_ = buffer.SetString(bufferData)
+			newBufferData := combinedData[:endpointUrlIndex] + newEndpointUrl + combinedData[endpointUrlIndex+len(endpointUrl):]
+			_ = buffer.SetString(newBufferData)
 		}
 	} else {
 		api.LogDebugf("The endpoint URL %s is not changed", endpointUrl)
@@ -492,6 +506,7 @@ func (f *filter) findEndpointUrl(bufferData string) (error, string) {
 // OnDestroy stops the goroutine
 func (f *filter) OnDestroy(reason api.DestroyReason) {
 	api.LogDebugf("OnDestroy: reason=%v", reason)
+	f.cachedResponseBody = nil
 	if f.serverName != "" && f.stopChan != nil {
 		select {
 		case <-f.stopChan: