The dify process executed without any errors, but the API did not return a value（dify流程执行没有报错，但是API没有返回值）

[zxjagnes]

When the same Dify process is invoked through the API, there is output content in the “Direct Reply” node at the end of the conversation log after execution. However, sometimes there is a return value in the API interface and conversation preview area, and sometimes there is no return value.
In direct replies, the value of answer is a string of JSON. When there is no return value, the JSON can be formatted normally, meaning that the symbols and other elements of JSON are not abnormal.

通过API调用同一条dify流程，执行后,对话日志中最后一个节点“直接回复”有输出内容,但是API接口以及对话预览区有时候有返回值，有时候没有返回值。

直接回复中，answer的值是一串json。没有返回值的时候，json是能够正常格式化的，相当于json的符号等是没有异常。

[zxjagnes]

This is the specific setting of the Dify process node

This is the specific Dify process node setting

[lysonober]

To be honest, I don’t quite understand what the problem is, @Dify_Forum_Helper, how do you understand it? And, what are your thoughts?

[Dify_Forum_Helper]

我理解成这样：

同一个工作流，用「调用 API」的方式触发时：

• 对话日志里最后一个「直接回复」节点总是有内容（answer 是一段 JSON 字符串）；
• 但 API 返回值 & 右侧对话预览，有时有结果、有时是空；
• 即使 API 没返回值，那段 JSON 依然是合法、可格式化的。

也就是说：工作流内部跑完没报错，最后节点也产出内容，但这段内容没被当成“最终回答”带回 API 响应，并且是「间歇性」发生，对吧？

---

我目前的初步推断 / 思路

因为我现在拿不到你实例的具体配置和运行日志，只能结合 Dify 的一般机制来推断几种最可能的原因，供你核对：

1. 「直接回复」节点配置的问题（引用字段不稳定）

   你右边的截图里写的是类似：
   输出 -> 代码执行 3./result

   常见坑是：

   • 代码执行 3 节点有时返回 result 字段，有时返回 result 为 null / undefined / 空字符串；
   • 或者 result 是一个复杂对象，而「直接回复」节点又做了额外的模板处理（比如 {{ result.xxx }}），当某个字段缺失时，整条 answer 变成空 / ""；
   • 在「对话日志」里看到的，是节点“执行结果”的原始输出，而 API 返回的是经过「直接回复」节点最终渲染后的 answer——两者不完全等价。

   建议你检查一下：

   • 在“直接回复”节点里到底填的是单纯 {{ nodes.<代码执行3>.result }}，还是做了更多处理？
   • 当 API 没有返回的时候，点开该次对话的「直接回复」节点详情，看「渲染后的 answer」是不是空字符串 / null。

2. JSON 字符串 vs. 结构化输出 / 严格 JSON 模式

   你提到 answer 是“一串 JSON 字符串”。这里有两种情况很关键：

   • 你是期望返回纯文本 JSON 字符串（即 content 就是 "{a: 1}" 这样的字符串）；
   • 还是配置了「结构化输出 / JSON 输出模式」，期望 Dify 把回答当作 JSON 解析，然后再生成响应？

   如果是第二种：

   • 一旦模型或代码返回的 JSON 多了字段 / 少了字段 / 类型不符，系统在解析时有可能直接判定失败，不把它当作可返回的 answer；
   • 这就会出现「日志里看到字符串没问题，但平台层面解析失败 → API 响应体中没有 answer」。

   核心问题在于：日志展示的是“原始文本”，而 API 是看“平台成功解析之后的 answer”。

3. 多分支并行 + 最终回复合并时机的问题

   你的流程是：多个 LLM 节点并行 → 汇总到一个「代码执行 3」-> 再到「直接回复」。

   如果在代码节点里，是按「第一个结束的 LLM」/「某个条件」去选结果，再拼成 JSON，那有可能出现：

   • 某些调用中，所有分支都满足条件 → 拼出的 JSON 正常；
   • 某些调用中，部分分支结果为空 / 出错（但未显式抛异常）-> 代码逻辑返回了一个“空 JSON”或没有返回值（Python 默认 None），最后「直接回复」节点拿到的是空/无效值，因此 API 也没东西。

   日志侧看到的 “节点执行成功 ” 只代表没有代码异常，不代表你返回的数据业务上符合预期。

4. API 调用方式 / streaming 与否 / SDK 处理

   再确认两点：

   • 你是用哪一个接口？/v1/workflows/trigger 还是 chat-messages 类接口？
   • 是否使用了 stream=true 的流式返回？某些 SDK 或你自己的封装，如果流式返回里没正确处理 event: workflow_finished / data: ...，表面看就像“没返回值”。

   简单排查方式：

   • 直接用 curl 或 Postman 调一次同样的 API，看原始 HTTP 响应体里到底有没有 answer 字段；
   • 如果 Postman 有，而你代码没有，多半是客户端处理流式/事件流的逻辑问题，而不是 Dify 内部。

---

建议你可以先做的几个验证（不改太多流程）

1. 在「直接回复」节点前，再插一个调试用的「代码执行」节点：

   • 代码里 print(result) 或把你当前要回复的内容封装成一个带时间戳的结构：

     return {
       "debug_time": "{{ now }}",
       "raw_result": <你现在要放进直接回复的那段值>
     }
     

   • 然后「直接回复」节点只简单输出这个 debug 字段，先确认每一次 API 调用时，这个值是否始终非空。

2. 把「直接回复」节点的输出先改成一个固定文本 + 插值，比如：

   调试：{{ nodes["代码执行 3"].result | tojson }}
   

   • 这样即使 result 是 null，你也能从日志 & API 中看到是“调试：null / 调试：{}”，避免“完全空白”。

3. 贴出一段有问题时的完整响应（脱敏）

   如果方便，你可以在后续回帖中贴一段：

   • 正常返回时的 API 响应 JSON；
   • 不正常时的 API 响应 JSON；
   • 各自对应那一条对话日志中，「直接回复」节点里看到的 answer 具体内容。

   我可以根据这三者的差异，基本能判断是：

   • 平台解析 / 严格 JSON 校验导致的丢弃；
   • 还是你代码节点/模板在「有些 case 下实际上生成了空 answer」。

---

简单总结给 lysonober：

我目前的理解：

• 问题不是“节点没执行”，而是“日志里看到 answer，但 API 响应体里有时没有 answer”；
• 构造上是多路 LLM → 一个代码节点 → 一个直接回复节点，answer 是 JSON 字符串；
• 高概率是：
  1）直接回复节点引用的字段有时为空 / 类型不对；
  2）或启用了结构化/JSON 输出校验，导致平台在某些调用中丢弃了不符合 schema 的 JSON；
  3）或是流式响应在调用端被错误消费，看起来像“没返回”。

后面只要楼主能补充：

• 版本号、
• 直接回复节点的具体模板、
• 一条“有返回”和“一条“无返回”的原始 HTTP 响应对比，

就能进一步锁定原因。

[zxjagnes]

Current Dify version: 1.11.0

The specific content of the ‘Direct Reply’ node is (as shown below)

Additionally, it can be confirmed in Code Execution 3 that the output result is a normal, error-free JSON string output in Markdown format.

There is no HTTP response, meaning there is no return directly, and the return interface was not called.

[Dify_Forum_Helper]

The supplementary information is crucial, thank you!

Let’s summarize the key information first:

• Dify Version: 1.11.0
• Workflow Structure: Multi-path LLM → Code Execution 3 → “Direct Reply”
• Direct Reply Node Configuration: Simply references {{ Code Execution 3.result }}
• You confirm: The result of Code Execution 3 is always a normal, parsable JSON string (in Markdown format)
• When abnormal: The HTTP interface completely returns nothing, as if the request is hanging / timing out, with no response body received.

With these points combined, the problem is no longer “the answer field is sometimes empty,” but rather:

The workflow completes internally, but occasionally freezes/fails when writing the “Direct Reply” result back to the HTTP response (possibly a backend bug or specific content triggering an exception), causing the client to receive no HTTP response.

Below, I’ll explain by “suspected cause + suggested troubleshooting/mitigation methods,” which you can try step by step:

---

1. First, rule out: Is the request still running, and you just haven’t waited long enough?

In 1.11.0, if a Workflow has many nodes and all are calling LLMs in series/parallel, an execution can sometimes take several minutes. Please confirm two points:

1. For those requests that “have no return”:

   • Does the workflow log immediately show that the “Direct Reply” node has executed successfully?
   • Or does the log also wait a long time before “Direct Reply” turns green ?

2. On the client side:

   • Have you set a timeout yourself (e.g., HTTP client 30-second timeout)?
     If so, you might have actively disconnected the request before the server returned, which would also appear as “no return at all” locally.

Suggested quick test:

• Use Postman / curl to send the same API request, and set the HTTP client timeout longer (e.g., 300 seconds):
  • If Postman eventually gets a result, but your code doesn’t, it’s likely a timeout setting issue in your code;
  • If Postman also keeps hanging without returning, then Dify is truly “not writing back a response.”

---

2. Check the “Session Log Details” for the failed attempt for any exception stack traces.

Although you said “the workflow execution did not report an error,” there are two situations that need special attention:

1. Entire execution log:
   Open the “Details” / “Trace” in the upper right corner of the “Conversation Log” and check the very bottom for small red markers like “System Error” or “Internal Error.”

2. Direct Reply node internal log:

   • Click on the “Direct Reply” node and see if there are “Rendering failed” or “Template error” prompts;
   • For example: variable not found, Jinja template error, etc. Sometimes the UI only shows a yellow/red small icon, which may not be obvious.

If you see error messages in these places, you can paste them (be sure to anonymize), and I can help you translate them into specific causes.

---

3. Perform a small modification test for “result is a JSON string.”

Because you said result is “a Markdown-formatted JSON string,” we need to rule out two things:

1. Whether there are Markdown symbols before and after the JSON (e.g., json code block, backticks, prefix text, etc.). It looks “formattable” in the conversation log, but the backend might have extra logic when processing/recording;
2. Certain special characters (control characters, extremely long single lines, special Unicode) occasionally trigger serialization exceptions.

I suggest you make a minimal change first:

In Code Execution 3, change the return to be a real object, not a “JSON string”:

import json

# Assuming your current result is a string json_str
data = json.loads(json_str)   # First convert to a Python object

return {
    "safe_result": data
}

Then change the “Direct Reply” node to:

{{ nodes["代码执行 3"].outputs.safe_result | tojson }}

Or simply output a fixed text:

Debug: OK

Test in two steps:

1. Only output fixed text Debug: OK:
   • If there are no more “no return” situations at this point, it means the problem is highly concentrated on “the content of that JSON string itself”;
2. Then change to output the object using | tojson:
   • If it’s also stable, it means the previous method of “directly using Markdown JSON strings” might trigger some serialization/encoding exception in extreme cases.

---

4. See if it’s an “Asynchronous Trigger / Webhook” type of issue.

You previously said “the HTTP response with no return, is directly no return, no return interface was called.” I want to confirm whether you are using:

• Standard synchronous interface (e.g., /v1/workflows/trigger, /v1/chat-messages, expecting an answer to be returned immediately);
• Or are you using “asynchronous mode” (e.g., configured Webhook, polling results, etc.), in which case the normal behavior is that the initial call does not directly include the result.

If you are unsure, you can paste the URL you are calling, such as:

POST /v1/workflows/trigger

Or:

POST /v1/workflows/events

Such paths (without domain, token), and I will help you determine.

---

5. Combining with the status of 1.11.0: It is recommended to add an extra layer of “protection” + “logging.”

The current phenomenon seems to be:

• Most of the time everything is normal;
• Occasionally, “a certain input + certain JSON content” causes an internal exception (or timeout) when writing back the response, the UI only shows the node executed successfully, but the HTTP channel hangs.

Before you can immediately upgrade / troubleshoot the source code, you can first use “defensive coding” to try to avoid triggering edge cases:

1. In Code Execution 3, perform a fallback process for the result that will eventually be returned:

   import json
   from datetime import datetime
   
   def safe_result(raw):
       try:
           # If it's already a dict, return directly
           if isinstance(raw, dict):
               return raw
           # If it's a string, try to parse
           if isinstance(raw, str):
               return json.loads(raw)
       except Exception as e:
           return {
               "error": "json_parse_failed",
               "message": str(e),
               "raw": raw,
               "time": datetime.utcnow().isoformat()
           }
       # Other types are wrapped directly
       return {
           "wrapped": raw,
           "time": datetime.utcnow().isoformat()
       }
   
   # Your original generated json string is called raw_json
   return {
       "result": safe_result(raw_json)
   }
   

2. In the “Direct Reply” node, uniformly use:

   {{ nodes["代码执行 3"].outputs.result | tojson }}
   

The advantage of doing this is:

• Even if strange content is encountered, at most you will get a JSON containing error: json_parse_failed, instead of the entire HTTP request having no return.

---

6. If convenient, please provide two more pieces of information.

To further determine whether it’s a “content issue” or a “backend bug,” you can later supplement:

1. A complete HTTP response (after anonymization) from a “normal return,” and the corresponding answer text from the “Direct Reply” node for that instance;
2. A “conversation log screenshot” (from start to the direct reply node, confirming all nodes are green checkmarks) for an instance where there was “no return,” especially the content displayed inside the direct reply node.

Based on these two sets of comparisons, I can determine:

• Whether it’s an issue caused by specific size (particularly long JSON);
• Whether it contains special characters / Emoji / control characters;
• Whether there’s a clear pattern (e.g., only hangs when certain LLM branches generate specific content).

---

Summary of current suggested operation order

1. Use Postman/curl to directly call the API, extend the timeout, and confirm whether Dify truly isn’t responding or if the client is timing out.
2. Modify the “Direct Reply” node to first output fixed text, and see if “empty HTTP returns” still occur.
3. Change the JSON to “object + tojson output” to avoid directly passing Markdown JSON strings.
4. Add safety wrappers and error information in the code node to prevent internal exceptions due to extreme JSON content.
5. If the problem disappears after steps 2 and 3, you might consider this a content-related bug in 1.11.0. It is recommended to upgrade to a higher version if conditions permit, or report this issue to GitHub with a reproducible example.

If you are willing, you can try step 2 first: change “Direct Reply” to fixed text, and see if “completely no return” still occurs in the next few dozen calls; then we can analyze further together once you have results.

[zxjagnes]

Confirm that Dify genuinely returned no results, rather than a client timeout.

Additionally, all nodes appear normal in the session log details.

[Dify_Forum_Helper]

Key information re-confirmation:

• You have confirmed with Postman / curl or similar tools that: for those requests that “did not return”, the server indeed never terminates or returns any HTTP response (it’s not a client timeout).
• In the session logs: all nodes, including the final “Direct Reply”, show a green checkmark , with no error messages.
• The direct reply is simply: {{ 代码执行 3.result }}, and the upstream code node outputs “a very long piece of text” (the main body of a contract), not the JSON string you mentioned before.

Combining with the screenshot you just posted, it’s clear that the final direct reply is a large block of Chinese contract text—meaning that what’s ultimately written back to HTTP in this process is an extremely long text, with extreme length and character types (punctuation, special symbols, etc.).

In a 1.11.0 scenario like this, the most likely situation is:

Certain specific inputs + a particularly long piece of content, at the layer of “writing the final result back to the HTTP response”, triggered a backend exception (e.g., serialization, encoding, or gateway limits).
The log interface only marks the node as “execution successful”, but the layer that actually writes HTTP failed, so the client never receives a response.

Since I currently don’t have access to your instance’s backend logs, I can only provide a set of troubleshooting and mitigation solutions more targeted at the current phenomenon. You can try them in order of priority:

---

One-step “Verification Idea”: Shorten the final output to see if the problem disappears

Don’t worry about JSON yet; first, just verify “if it’s caused by content length / the content itself.”

1. Directly change “Direct Reply” to a fixed short text

Temporarily change it to:

调试：OK

Keep other nodes (LLM, Code Execution) unchanged. Then:

1. Call this workflow dozens of times consecutively;
2. Observe if the entire HTTP request still fails to return.

• If this no longer causes “stuck without returning”:
  It can basically be confirmed that the problem is strongly related to “that large block of text being returned” (length or characters).
• If it still occasionally gets stuck:
  Then it’s not a content issue, but more like a concurrency, connection, or reverse proxy configuration issue. In this case, you should check Nginx / reverse proxy / gunicorn logs.

---

2. If “fixed short text” is stable, then gradually put your content back

2.1 “Compress / Normalize” the result in the code node before replying

Your current 代码执行 3 (Code Execution 3) likely concatenates multiple LLM contents and directly returns a long string of text.
It is recommended to do a simple wrapper, put the actual content to be output into a field, and set an upper limit on the length:

MAX_LEN = 8000  # Set an arbitrary upper limit for now, e.g., 8k characters, adjust according to your business
# Assuming final_text is your concatenated complete contract text
text = final_text

# Truncate if too long, and mark it (just for verification)
truncated = False
if len(text) > MAX_LEN:
    text = text[:MAX_LEN]
    truncated = True

return {
    "text": text,
    "length": len(final_text),
    "truncated": truncated,
}

Then, the “Direct Reply” node only outputs:

{{ nodes["代码执行 3"].outputs.text }}

Observe two things:

1. Whether the HTTP non-return situation disappears after using this “text field with an upper limit”;
2. If requests where truncated == True also consistently no longer get stuck, it indicates that “overly long content” is very likely triggering the problem at some layer.

If your business absolutely requires returning the entire long text, then consider splitting it (see next point).

---

3. Try “segmenting the return” to see if the problem only occurs with extreme lengths

Make another version (if step 2 proves it’s related to length):

In the code node, break the long text into an array:

CHUNK_SIZE = 2000

chunks = []
for i in range(0, len(final_text), CHUNK_SIZE):
    chunks.append(final_text[i:i+CHUNK_SIZE])

return {
    "chunks": chunks,
    "total_len": len(final_text),
    "chunk_count": len(chunks),
}

Change “Direct Reply” to only return a JSON string describing these chunks, instead of directly stuffing the entire large text:

{{ nodes["代码执行 3"].outputs | tojson }}

If this also remains stable, it means that “single-field ultra-long text” is what’s truly causing trouble, not the process itself.
You can then, in your own business:

• Either only return meta information + storage ID in Dify (e.g., put the full text into your own storage and return a URL / key);
• Or change to multi-turn conversations to return in batches.

---

4. Check gateway / reverse proxy / timeout and body size limits

Because you have already confirmed:

• On the Dify server side, nodes “seem” to finish normally;
• But the HTTP link just doesn’t terminate or return.

Besides application bugs, another common cause for such problems is intermediate layer restrictions:

• Nginx / Traefik and other reverse proxies’:
  • proxy_read_timeout
  • client_max_body_size
  • etc.;
• Backend WSGI / ASGI server (gunicorn, uvicorn)'s:
  • worker timeout;
  • single response body size / buffer limits.

If you installed using the official docker-compose / helm, it is recommended to:

1. Check the logs of the gateway container / Nginx container to see if there are any obvious errors during the “no return” instances;
2. Increase relevant timeout times and body limits, then test again.

---

5. If convenient, it is recommended to supplement the characteristics of one successful / one failed “input”

No need to paste the actual full contract text, just state the visible differences between the two types of calls:

• For example:
  • For the times that returned: text length was about 2–3k characters;
  • For the times that didn’t return: text was 1–20k characters, containing many special punctuation marks, parentheses, blank lines, etc.;
• Or:
  • The problem only occurs when certain LLM branches produce “particularly long paragraphs.”

I can use these characteristics to further determine whether it’s a length issue or whether certain special characters/encodings are more likely to trigger the problem (e.g., certain invisible control characters, ultra-long continuous lines, etc.).

---

6. What to do if it’s confirmed to be a “content-related Dify 1.11.0 bug”

Once you have verified through the steps above that:

• Shortening, segmenting, | tojson and other methods work fine;
• Only when “a particularly long block of text” is directly inserted into “Direct Reply” does it occasionally hang;

Then it can basically be concluded that this is a bug in 1.11.0 in certain content scenarios. Next, it is recommended to:

1. Package and organize the “minimum reproducible process” and a redacted sample long text;
2. Create an issue on GitHub langgenius/dify: specify version 1.11.0, call method (which API), whether streaming, and the phenomenon of “all nodes successful but HTTP not returning”;
3. At the same time, deploy solutions like “segmenting/truncating/only returning ID” in production to avoid affecting business.

---

Summary

From all your current screenshots and descriptions:

• “Workflow internal completely normal” + “HTTP occasionally not returning” + “last hop is extremely long text”,
  makes me lean towards this being a response write-back issue triggered by length / specific characters, rather than a misconfiguration of your workflow.
• The fastest verification method is:
  First change the final direct reply to extremely short fixed text, to see if the problem immediately disappears; if so, then gradually restore the content to see at what “length / form” it starts to become unstable.

You can first try the “Direct Reply = 调试：OK” (Debug: OK) version, run it multiple times, and see if the “no HTTP return” situation no longer occurs; once you have results, we can then refine the next steps.

[972449665]

I also encountered the same problem Dify process executed without errors, but the API returned no value. I called the workflow through the Dify API, and the interface returned empty.

[972449665]

I also encountered the same problem, and it appears intermittently.

[fatelei]

please supply your dsl to debug

[972449665]

Intermittently, the API does not respond, making it impossible to upload DSL

[zxjagnes]

I ran the same Dify process using the input data that previously returned empty. I ran it over 60 times specifically to reproduce this issue, but it always returned normally.

What Dify version are you using?

[972449665]

I cannot reproduce this issue; it reappears intermittently.

[972449665]

Appears again