Help: When executing chatflow on the CODE, there is an Error: 'ascii' codec can't encode character '\ufffd'

[xiayinhai-pacvue]

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1. Is this request related to a challenge you're experiencing? Tell me about your story.

We install dify in the eks(1.33), when we run the on the CODE with chatflow, there will failed.

We try to add some lang env for api, sanbox, worker, but it also failed.

the error:
Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: 'ascii' codec can't encode character '\ufffd' in position 0: ordinal not in range(128) )

the variables which we tried to add:

- name: PYTHONIOENCODING
    value: "utf-8:ignore"
  - name: LANG
    value: "C.UTF-8"
  - name: LC_ALL
    value: "C.UTF-8"
  - name: LC_CTYPE
    value: "C.UTF-8"
  - name: LC_MESSAGES
    value: "C.UTF-8"
  - name: LC_MONETARY
    value: "C.UTF-8"
  - name: LC_NUMERIC
    value: "C.UTF-8"
  - name: LC_TIME
    value: "C.UTF-8"
  - name: LC_COLLATE
    value: "C.UTF-8"
  - name: PYTHONUNBUFFERED
    value: "1"
  - name: PYTHONDONTWRITEBYTECODE
    value: "1"
  - name: PYTHONPATH
    value: "/app"
  - name: PYTHONHASHSEED
    value: "random"
  - name: PYTHONFAULTHANDLER
    value: "1"
  - name: PYTHONASYNCIODEBUG
    value: "0"
  - name: PYTHONWARNINGS
    value: "ignore"
  - name: PYTHONUTF8
    value: "1"
  - name: PYTHONLEGACYWINDOWSSTDIO
    value: "utf-8"
  - name: PYTHONLEGACYWINDOWSFSENCODING
    value: "utf-8"

2. Additional context or comments

No response

[dosubot[bot]]

Hi @xiayinhai-pacvue! I'm Dosu and I’m helping the dify team.

The error is caused by the sandbox container's environment defaulting to ASCII encoding, not by Dify's code. To fix this, set the following environment variables in your sandbox container (and any related API/worker containers): LANG=en_US.UTF-8, LC_ALL=en_US.UTF-8, and PYTHONIOENCODING=utf-8. Avoid using C.UTF-8—it may not be supported in all base images and can cause issues example.

If you're using a Debian/Ubuntu-based image, make sure to install and generate the locale inside the container:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
ENV PYTHONIOENCODING=utf-8
RUN apt-get update && apt-get install -y locales && locale-gen en_US.UTF-8

For Alpine-based images:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
ENV PYTHONIOENCODING=utf-8
RUN apk add --no-cache libc6-compat

After updating, rebuild and redeploy your containers. Then, exec into the running sandbox container and run locale and env to confirm UTF-8 is active reference.

If the issue persists, upgrade to Dify v1.0.1 or later, as recent releases include fixes for Unicode handling in code execution nodes reference. If you still see errors, enable debug logs and check for encoding-related warnings.

Let me know if you need more details on updating your deployment!

To reply, just mention @dosu.

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[xiayinhai-pacvue]

We used the images from docker hub, tried these 2 version images; and now we use the version 1.7.1, it has been add those env in docker images.

langgenius/dify-web:1.7.1
langgenius/dify-api:1.7.1
langgenius/dify-sandbox:0.2.12
langgenius/dify-plugin-daemon:0.2.0-local

langgenius/dify-web:1.6.0
langgenius/dify-api:1.6.0
langgenius/dify-sandbox:0.2.12
langgenius/dify-plugin-daemon:0.1.3-local

this is the from 1.7.1

root@dify-worker-5cbdf5b9b-kdj5l:/app/api# locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=en_US.UTF-8
root@dify-worker-5cbdf5b9b-kdj5l:/app/api# locale -a
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_COLLATE to default locale: No such file or directory
C
C.utf8
POSIX
root@dify-worker-5cbdf5b9b-kdj5l:/app/api# echo $PYTHONIOENCODING
utf-8

these are from version 1.6.0

root@dify-worker-7b4bf658df-2tnzn:/app/api# locale -a
C
C.utf8
POSIX
root@dify-worker-7b4bf658df-2tnzn:/app/api# locale
LANG=C.UTF-8
LANGUAGE=
LC_CTYPE="C.UTF-8"
LC_NUMERIC="C.UTF-8"
LC_TIME="C.UTF-8"
LC_COLLATE="C.UTF-8"
LC_MONETARY="C.UTF-8"
LC_MESSAGES="C.UTF-8"
LC_PAPER="C.UTF-8"
LC_NAME="C.UTF-8"
LC_ADDRESS="C.UTF-8"
LC_TELEPHONE="C.UTF-8"
LC_MEASUREMENT="C.UTF-8"
LC_IDENTIFICATION="C.UTF-8"
LC_ALL=
root@dify-worker-7b4bf658df-2tnzn:/app/api# echo $PYTHONIOENCODING

root@dify-worker-7b4bf658df-2tnzn:/app/api# 
root@dify-worker-7b4bf658df-2tnzn:/app/api# python3 -c "import sys; print(sys.stdout.encoding)"
utf-8

[dosubot[bot]]

Your containers set UTF-8 environment variables, but the en_US.UTF-8 locale is not actually generated or installed inside the images. This is why you see errors like “Cannot set LC_CTYPE to default locale” and only C, C.utf8, and POSIX in locale -a. As a result, Python may still default to ASCII and trigger encoding errors, even if the env vars look correct.

To fix this, you need to build custom images that both set the environment variables and generate the locale. For Debian/Ubuntu-based images, add these lines to your Dockerfile:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
ENV PYTHONIOENCODING=utf-8
RUN apt-get update && apt-get install -y locales && locale-gen en_US.UTF-8

For Alpine-based images, use:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
ENV PYTHONIOENCODING=utf-8
RUN apk add --no-cache libc6-compat

Then rebuild and redeploy your containers. After that, run locale -a and locale inside the running containers to confirm en_US.UTF-8 is available and active. This should resolve the encoding errors in chatflow code execution nodes reference.

Note: The official dify-sandbox image is prebuilt and does not expose its Dockerfile, so you cannot directly patch it. If you need this fixed in the sandbox, you’ll need to build your own image based on the official one, or request an update from the maintainers reference.

To reply, just mention @dosu.

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[xiayinhai-pacvue]

rebuild which images? sandbox or all images?

langgenius/dify-web:1.7.1
langgenius/dify-api:1.7.1
langgenius/dify-sandbox:0.2.12
langgenius/dify-plugin-daemon:0.2.0-local

[dosubot[bot]]

You only need to rebuild the sandbox image (langgenius/dify-sandbox) to resolve the encoding issue. The sandbox container is solely responsible for executing user code in chatflow workflows—the API, web, and plugin-daemon images just orchestrate and do not run user code themselves.

To fix the locale problem, build a custom sandbox image based on the official one, making sure to both set the environment variables (LANG and LC_ALL to en_US.UTF-8) and generate the locale inside the container. For Debian/Ubuntu-based images, add:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
RUN apt-get update && apt-get install -y locales && locale-gen en_US.UTF-8

For Alpine-based images, use:

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
RUN apk add --no-cache libc6-compat

Rebuild and redeploy only the sandbox container. This should resolve the 'ascii' codec error in chatflow code execution nodes. More details and examples are available in this issue.

To reply, just mention @dosu.

---

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[xiayinhai-pacvue]

Build with Dockerfile

FROM langgenius/dify-sandbox:0.2.12

ENV LANG=en_US.UTF-8
ENV LC_ALL=en_US.UTF-8
ENV PYTHONIOENCODING=utf-8

RUN apt-get update && \
    apt-get install -y locales && \
    locale-gen en_US.UTF-8 && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

And upgrade the sanbox, the same errors:
Run failed: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: 'ascii' codec can't encode character '\ufffd' in position 0: ordinal not in range(128) )

firstly we use this version, migration execute in api

langgenius/dify-web:1.6.0
langgenius/dify-api:1.6.0
langgenius/dify-sandbox:0.2.12
langgenius/dify-plugin-daemon:0.1.3-local

there is this error: Run failed: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: 'ascii' codec can't encode character '\ufffd' in position 0: ordinal not in range(128) )

tried to upgrade to this verison, migration execute in api

langgenius/dify-web:1.7.1
langgenius/dify-api:1.7.1
langgenius/dify-sandbox:0.2.12
langgenius/dify-plugin-daemon:0.2.0-local

[xiayinhai-pacvue]

And we tried to stop sanbox with setting replica to 0, it always show the error: Run failed: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: 'ascii' codec can't encode character '\ufffd' in position 0: ordinal not in range(128) ), so it seems this error is not related to sanbox?

[dosubot[bot]]

This error is still related to the sandbox. The Dify API never executes user code itself—it always tries to send code to the sandbox service. When the sandbox is stopped (replica set to 0), the API can't reach it and wraps the resulting network error (like connection refused or timeout) in a generic message. If there are any Unicode or encoding issues in the error message or traceback, those can show up as an 'ascii' codec error at the API layer—even though no code is actually being executed anywhere else.

So, the error means the sandbox is unavailable, and the API is just reporting the failure to connect, not running code itself or falling back to another executor. To resolve this, make sure the sandbox is running and reachable, and double-check locale/encoding settings in both the API and sandbox containers if you continue to see encoding-related errors. For more details, see this relevant discussion and the code handling logic.

To reply, just mention @dosu.

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[xiayinhai-pacvue]

But We also tried in local PC env with docker, we stop the sandbox in local PC, it shows timeout connection refused.
In ESK, we stopped the sandbox, it showed Run failed: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: 'ascii' codec can't encode character '\ufffd' in position 0: ordinal not in range(128) )

[xiayinhai-pacvue]

the locale/encoding
api

root@dify-api-8b4b9d975-xd2kp:/app/api# root@dify-api-8b4b9d975-xd2kp:/app/api# 
bash: root@dify-api-8b4b9d975-xd2kp:/app/api#: No such file or directory
root@dify-api-8b4b9d975-xd2kp:/app/api# 
root@dify-api-8b4b9d975-xd2kp:/app/api# 
root@dify-api-8b4b9d975-xd2kp:/app/api# 
root@dify-api-8b4b9d975-xd2kp:/app/api# locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=en_US.UTF-8
root@dify-api-8b4b9d975-xd2kp:/app/api# python3 -c "import sys; print(sys.stdout.encoding)"
utf-8
root@dify-api-8b4b9d975-xd2kp:/app/api# echo $PYTHONIOENCODING
utf-8

sanbox which re-build image as suggestion:

[ec2-user@ip-10-27-6-39 ~]$ kubectl exec -ti dify-sandbox-6d9897d69f-gnxdm -- bash
bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8): No such file or directory
root@dify-sandbox-6d9897d69f-gnxdm:/# locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=en_US.UTF-8
root@dify-sandbox-6d9897d69f-gnxdm:/# python3 -c "import sys; print(sys.stdout.encoding)"
utf-8
root@dify-sandbox-6d9897d69f-gnxdm:/# echo $PYTHONIOENCODING
utf-8
root@dify-sandbox-6d9897d69f-gnxdm:/# 

[dosubot[bot]]

Your containers set the correct UTF-8 environment variables, but the errors like Cannot set LC_CTYPE to default locale and the absence of en_US.UTF-8 in locale -a mean the locale was never actually generated or installed in the image. This is why Python and system tools still fall back to ASCII, causing encoding errors—even after rebuilding with the official dify-sandbox image as a base.

The official dify-sandbox image does not publish its Dockerfile, and adding locale generation steps on top of it may not work if the base image is too minimal or lacks required packages. The best workaround is to build your own sandbox image from a standard Debian/Ubuntu Python base, install all required dependencies, generate the locale, and copy in the sandbox code/entrypoint. Only then will en_US.UTF-8 appear in locale -a and locale errors disappear.

If you want to confirm, run locale -a in your running container—if you don't see en_US.UTF-8, the locale is still missing and Python will not use it, regardless of environment variables. If you need help with a custom Dockerfile or want to share logs from the sandbox container during code execution, I can help troubleshoot further.

For reference, this is a common issue with minimal Docker images and is not specific to Dify's code logic—it's about the underlying OS image and locale generation at build time. See related discussion.

To reply, just mention @dosu.

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[xiayinhai-pacvue]

Ok I will confirm more about locale in api and sandbox;

Supplement more, we add logger in https://github.com/langgenius/dify/blob/1.7.1/api/core/helper/code_executor/code_executor.py#L80, before raise post request we add some to log; it seems the header is invalid.

            logger.info(f"Executing code: {data}")
            logger.info(f"Headers: {headers}")
            logger.info(f"URL: {url}")
            logger.info(f"Timeout: {Timeout(
                    connect=dify_config.CODE_EXECUTION_CONNECT_TIMEOUT,
                    read=dify_config.CODE_EXECUTION_READ_TIMEOUT,
                    write=dify_config.CODE_EXECUTION_WRITE_TIMEOUT,
                    pool=None,
                )}")

2025-07-31 05:38:19,483.483 INFO [Thread-8 (_generate_worker)] [code_executor.py:80] - Executing code: {'language': <CodeLanguage.PYTHON3: 'python3'>, 'code': '\n# declare main function\n\ndef main(arg1: str, arg2: str) -> dict:\n    return {\n        "result": arg1 + arg2,\n    }\n\n\nimport json\nfrom base64 import b64decode\n\n# decode and prepare input dict\ninputs_obj = json.loads(b64decode(\'e30=\').decode(\'utf-8\'))\n\n# execute main function\noutput_obj = main(**inputs_obj)\n\n# convert output to json and print\noutput_json = json.dumps(output_obj, indent=4)\nresult = f\'\'\'<<RESULT>>{output_json}<<RESULT>>\'\'\'\nprint(result)\n', 'preload': '', 'enable_network': True}
2025-07-31 05:38:19,483.483 INFO [Thread-8 (_generate_worker)] [code_executor.py:81] - Headers: {'X-Api-Key': '�i=Z~v��\x10$00���WėZו��\x0b��Ya���v'}
2025-07-31 05:38:19,483.483 INFO [Thread-8 (_generate_worker)] [code_executor.py:82] - URL: http://dify-sandbox/v1/sandbox/run
2025-07-31 05:38:19,483.483 INFO [Thread-8 (_generate_worker)] [code_executor.py:83] - Timeout: Timeout(connect=10.0, read=60.0, write=10.0, pool=None)

[xiayinhai-pacvue]

X-Api-Key is error, change this variable and re deploy, it works.