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API calls chatflow, and after returning "ping", no more stream return events are pulled. #16503

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opened 2026-02-21 19:26:22 -05:00 by yindo · 3 comments
yindo commented 2026-02-21 19:26:22 -05:00
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Originally created by @xiaoyesoso on GitHub (Aug 27, 2025).

Self Checks

  • I have read the Contributing Guide and Language Policy.
  • This is only for bug report, if you would like to ask a question, please head to Discussions.
  • I have searched for existing issues search for existing issues, including closed ones.
  • I confirm that I am using English to submit this report, otherwise it will be closed.
  • 【中文用户 & Non English User】请使用英语提交，否则会被关闭 ：）
  • Please do not modify this template :) and fill in all the required fields.

Dify version

1.8.0

Cloud or Self Hosted

Self Hosted (Docker)

Steps to reproduce

For details, see: https://github.com/langgenius/dify/issues/24268

Version 1.7.1 was working correctly. This issue reappeared in version 1.7.2 and persists in version 1.8.0.

✔️ Expected Behavior

Hopefully, calling ChatFlow using the API will succeed in the above situation.

❌ Actual Behavior

No response

Originally created by @xiaoyesoso on GitHub (Aug 27, 2025). ### Self Checks - [x] I have read the [Contributing Guide](https://github.com/langgenius/dify/blob/main/CONTRIBUTING.md) and [Language Policy](https://github.com/langgenius/dify/issues/1542). - [x] This is only for bug report, if you would like to ask a question, please head to [Discussions](https://github.com/langgenius/dify/discussions/categories/general). - [x] I have searched for existing issues [search for existing issues](https://github.com/langgenius/dify/issues), including closed ones. - [x] I confirm that I am using English to submit this report, otherwise it will be closed. - [x] 【中文用户 & Non English User】请使用英语提交，否则会被关闭 ：） - [x] Please do not modify this template :) and fill in all the required fields. ### Dify version 1.8.0 ### Cloud or Self Hosted Self Hosted (Docker) ### Steps to reproduce For details, see: https://github.com/langgenius/dify/issues/24268 Version 1.7.1 was working correctly. This issue reappeared in version 1.7.2 and persists in version 1.8.0. ### ✔️ Expected Behavior Hopefully, calling ChatFlow using the API will succeed in the above situation. ### ❌ Actual Behavior _No response_
yindo added the 🌊 feat:workflow label 2026-02-21 19:26:22 -05:00
yindo closed this issue 2026-02-21 19:26:22 -05:00
yindo commented 2026-02-21 19:26:22 -05:00
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@dosubot[bot] commented on GitHub (Aug 27, 2025):

The streaming mechanism in Dify is event-driven: the API should continuously stream events like node started, node succeeded, and periodic "ping" events to keep the connection alive. If you only receive "ping" events and then the stream stops, it usually means the workflow engine or a node worker is stalled, deadlocked, or hitting a timeout—especially with long-running nodes like HTTP requests. The "ping" event itself is normal and does not cause streaming to stop; streaming only halts on error, stop, or timeout events see code reference.

Since this issue appeared after 1.7.1 and persists in 1.8.0, but works via the web interface, it's likely related to environment or configuration changes. For Docker/self-hosted setups, make sure your NGINX proxy config disables buffering and supports HTTP/1.1 streaming: set proxy_buffering off;, proxy_http_version 1.1;, and proxy_set_header Connection ""; see nginx config. Also, verify that your plugin daemon and vLLM backend run with streaming-capable servers (gunicorn/uvicorn in async mode, not WSGI-only).

If the config is correct, check for differences in proxy, network, or container setup between working and non-working environments, and review logs for errors or timeouts. Testing with curl --no-buffer inside the container to the plugin daemon and vLLM endpoints can help isolate where streaming breaks see troubleshooting steps.

If you use conditional branches in your workflow, ensure you aggregate variables properly, as missing aggregation can also cause streaming to stop despite "ping" events see related issue.

Let me know if you need help interpreting logs or config snippets!

To reply, just mention @dosu.

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@dosubot[bot] commented on GitHub (Aug 27, 2025): <!-- Answer --> The streaming mechanism in Dify is event-driven: the API should continuously stream events like node started, node succeeded, and periodic "ping" events to keep the connection alive. If you only receive "ping" events and then the stream stops, it usually means the workflow engine or a node worker is stalled, deadlocked, or hitting a timeout—especially with long-running nodes like HTTP requests. The "ping" event itself is normal and does not cause streaming to stop; streaming only halts on error, stop, or timeout events [see code reference](https://github.com/langgenius/dify/blob/56c51f01123b4ae3419478f38b46464879a19826/api/core/app/apps/base_app_queue_manager.py). Since this issue appeared after 1.7.1 and persists in 1.8.0, but works via the web interface, it's likely related to environment or configuration changes. For Docker/self-hosted setups, make sure your NGINX proxy config disables buffering and supports HTTP/1.1 streaming: set `proxy_buffering off;`, `proxy_http_version 1.1;`, and `proxy_set_header Connection "";` [see nginx config](https://github.com/langgenius/dify-official-plugins/issues/1188). Also, verify that your plugin daemon and vLLM backend run with streaming-capable servers (gunicorn/uvicorn in async mode, not WSGI-only). If the config is correct, check for differences in proxy, network, or container setup between working and non-working environments, and review logs for errors or timeouts. Testing with `curl --no-buffer` inside the container to the plugin daemon and vLLM endpoints can help isolate where streaming breaks [see troubleshooting steps](https://github.com/langgenius/dify-official-plugins/issues/1172). If you use conditional branches in your workflow, ensure you aggregate variables properly, as missing aggregation can also cause streaming to stop despite "ping" events [see related issue](https://github.com/langgenius/dify/issues/15351). Let me know if you need help interpreting logs or config snippets! <!-- Dosu Comment Footer --> *To reply, just mention [@dosu](https://go.dosu.dev/dosubot).* --- <sup>How did I do? [Good](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=great_response) | [Irrelevant](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=irrelevant_answer) | [Incorrect](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=incorrect_sources) | [Verbose](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=too_verbose) | [Hallucination](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=hallucination) | [Report 🐛](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=bug_report) | [Other](https://app.dosu.dev/response-feedback/1b2b5b96-a628-4872-b9eb-e719027fb82d?feedback_type=other)</sup>&nbsp;&nbsp;[![Chat with Dosu](https://dosu.dev/dosu-chat-badge.svg)](https://app.dosu.dev/6088a4f4-073a-43f3-b3d4-4f06fb0c05a0/ask?utm_source=github)&nbsp;[![Join Discord](https://img.shields.io/badge/join-5865F2?logo=discord&logoColor=white&label=)](https://go.dosu.dev/discord-bot)&nbsp;[![Share on X](https://img.shields.io/badge/X-share-black)](https://twitter.com/intent/tweet?text=%40dosu_ai%20helped%20me%20solve%20this%20issue!&url=https%3A//github.com/langgenius/dify/issues/24675)
yindo commented 2026-02-21 19:26:22 -05:00
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@v-49 commented on GitHub (Sep 2, 2025):

Test Case 1: Simple Workflow (Working)
When we create a new, simple test workflow (e.g., containing only a Start node and an Answer node), the API call successfully streams the response as expected. We receive events incrementally.
Test Case 2: Complex Workflow (Not Working)
However, when we use our original, more complex workflow, the API call does not stream. The connection remains open, but we only receive the full, non-streamed response at the very end, once the entire workflow has completed its execution.

@v-49 commented on GitHub (Sep 2, 2025): Test Case 1: Simple Workflow (Working) When we create a new, simple test workflow (e.g., containing only a Start node and an Answer node), the API call successfully streams the response as expected. We receive events incrementally. Test Case 2: Complex Workflow (Not Working) However, when we use our original, more complex workflow, the API call does not stream. The connection remains open, but we only receive the full, non-streamed response at the very end, once the entire workflow has completed its execution.
yindo commented 2026-02-21 19:26:22 -05:00
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@dosubot[bot] commented on GitHub (Oct 3, 2025):

Hi, @xiaoyesoso. I'm Dosu, and I'm helping the Dify team manage their backlog and am marking this issue as stale.

Issue Summary:

  • You reported that after upgrading Dify from v1.7.1 to v1.7.2 and v1.8.0, API calls to ChatFlow only return a "ping" event without further streaming.
  • This causes the API to stop responding as expected during streaming.
  • I suggested that stalled or deadlocked workflow nodes might be the cause, and recommended checking Docker/Nginx proxy configurations and async server setups.
  • Another user confirmed that simple workflows stream correctly, but complex workflows do not stream and only return a full response after completion, indicating a possible relation to workflow complexity or node handling.

Next Steps:

  • Please let me know if this issue is still relevant with the latest version of Dify by commenting here to keep the discussion open.
  • Otherwise, this issue will be automatically closed in 15 days.

Thank you for your understanding and contribution!

@dosubot[bot] commented on GitHub (Oct 3, 2025): Hi, @xiaoyesoso. I'm [Dosu](https://dosu.dev), and I'm helping the Dify team manage their backlog and am marking this issue as stale. **Issue Summary:** - You reported that after upgrading Dify from v1.7.1 to v1.7.2 and v1.8.0, API calls to ChatFlow only return a "ping" event without further streaming. - This causes the API to stop responding as expected during streaming. - I suggested that stalled or deadlocked workflow nodes might be the cause, and recommended checking Docker/Nginx proxy configurations and async server setups. - Another user confirmed that simple workflows stream correctly, but complex workflows do not stream and only return a full response after completion, indicating a possible relation to workflow complexity or node handling. **Next Steps:** - Please let me know if this issue is still relevant with the latest version of Dify by commenting here to keep the discussion open. - Otherwise, this issue will be automatically closed in 15 days. Thank you for your understanding and contribution!
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Reference: langgenius/dify#16503
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