[Bugfix] fix missing 'finish_reason': null in streaming chat (#19662)

chaunceyjiang · web-flow · commit 836d4ce140a6 · 2025-06-16T14:10:39.000Z
Signed-off-by: chaunceyjiang &lt;chaunceyjiang@gmail.com&gt;
diff --git a/vllm/entrypoints/openai/serving_chat.py b/vllm/entrypoints/openai/serving_chat.py
@@ -873,7 +873,7 @@ async def chat_completion_stream_generator(
                             total_tokens=num_prompt_tokens + completion_tokens,
                         )
 
-                    data = chunk.model_dump_json(exclude_none=True)
+                    data = chunk.model_dump_json(exclude_unset=True)
                     yield f"data: {data}\n\n"
 
             # once the final token is handled, if stream_options.include_usage

Original file line number	Diff line number	Diff line change
`@@ -873,7 +873,7 @@ async def chat_completion_stream_generator(`
`873`	`873`	`total_tokens=num_prompt_tokens + completion_tokens,`
`874`	`874`	`)`
`875`	`875`
`876`		`- data = chunk.model_dump_json(exclude_none=True)`
	`876`	`+ data = chunk.model_dump_json(exclude_unset=True)`
`877`	`877`	`yield f"data: {data}\n\n"`
`878`	`878`
`879`	`879`	`# once the final token is handled, if stream_options.include_usage`