diff --git a/src/google/adk/cli/adk_web_server.py b/src/google/adk/cli/adk_web_server.py
index c3b81b287b..ee3ccf6143 100644
--- a/src/google/adk/cli/adk_web_server.py
+++ b/src/google/adk/cli/adk_web_server.py
@@ -1623,9 +1623,23 @@ async def event_generator():
                     "Generated event in agent run streaming: %s", sse_event
                 )
                 yield f"data: {sse_event}\n\n"
+
+          # Send termination signal after all events have been streamed
+          yield "data: [DONE]\n\n"
         except Exception as e:
           logger.exception("Error in event_generator: %s", e)
-          yield f"data: {json.dumps({'error': str(e)})}\n\n"
+          # Yield a proper Event object for the error
+          error_event = Event(
+              author="system",
+              content=types.Content(
+                  role="model", parts=[types.Part(text=f"Error: {e}")]
+              ),
+          )
+          yield (
+              "data:"
+              f" {error_event.model_dump_json(by_alias=True, exclude_none=True)}\n\n"
+          )
+          yield "data: [DONE]\n\n"
 
       # Returns a streaming response with the proper media type for SSE
       return StreamingResponse(
diff --git a/tests/unittests/cli/test_fast_api.py b/tests/unittests/cli/test_fast_api.py
index 1ab1d41f47..d1cbf53304 100755
--- a/tests/unittests/cli/test_fast_api.py
+++ b/tests/unittests/cli/test_fast_api.py
@@ -1094,7 +1094,7 @@ async def run_async_with_artifact_delta(
   sse_events = [
       json.loads(line.removeprefix("data: "))
       for line in response.text.splitlines()
-      if line.startswith("data: ")
+      if line.startswith("data: ") and line != "data: [DONE]"
   ]
 
   assert len(sse_events) == 2