Error 500 when Uploading Source Strings via wlc (--method replace/source)

[ddeveloperuch]

Hello Weblate team,
I'm using the Python Weblate Client (wlc) to interact with our Weblate instance.
The source language for our component is configured as English (Developer). I'm attempting to upload updated source strings using the --method source flag. However, I'm encountering the following errors:

"component": "companyXYZ/app-ios-project/en"
"method": "source"

Uploading en.xliff for language: en
{
  "error": "HTTP error 400: Bad Request",
  "details": {
    "type": "validation_error",
    "errors": [
      {
        "code": "invalid",
        "detail": "Source upload is supported only on source language.",
        "attr": "method"
      }
    ]
  },
  "upload": {
    "file": "en.xliff",
    "component": "companyXYZ/app-ios-project/en",
    "method": "source",
    "input_path": "_Translations/en.xliff"
  },
  "status": "❌ Failed to upload en.xliff",
  "command": [
    "wlc",
    "--url", "https://weblate.companyXYZ.com/api/",
    "--key", "wlu_abcdefg1234567890abcdefg",
    "upload",
    "companyXYZ/app-ios-project/en",
    "--input", "_Translations/en.xliff",
    "--method", "source"
  ],
  "exit_status": 1
}

"component": "companyXYZ/app-ios-project"
"method": "source"

{
  "upload": {
    "file": "en.xliff",
    "language": "en",
    "component": "companyXYZ/app-ios-project",
    "input_path": "_Translations/en.xliff",
    "method": "source"
  },
  "error": {
    "message": "This command is supported only at translation level",
    "type": "invalid_usage",
    "hint": "You tried to upload a translation-format file (XLIFF) using --method source, which is only allowed for source files and only at the base (source) component."
  },
  "status": "❌ Failed to upload en.xliff",
  "command": [
    "wlc",
    "--url", "https://weblate.companyXYZ.com/api/",
    "--key", "wlu_abcdefg1234567890abcdefg",
    "upload",
    "companyXYZ/app-ios-project",
    "--input", "_Translations/en.xliff",
    "--method", "source"
  ],
  "exit_status": 1
}

Could you please advise:

1. Whether .xliff files are supported for source string uploads?
2. What is the correct target component or language path for uploading source strings when using the English (Developer) source language?
3. Whether an alternative format (e.g., .strings or .pot) should be used instead for --method source?

[nijel]

Whether .xliff files are supported for source string uploads?

Why not just use replace upload? See https://docs.weblate.org/en/latest/user/files.html#import-methods for a detailed explanation of methods.

What is the correct target component or language path for uploading source strings when using the English (Developer) source language?

en_devel, you can see it in both API and UI.

[ddeveloperuch]

@nijel I’ve tried both of your suggestions, but unfortunately I’m receiving 500 Internal Server Error response from the server.

"component": "companyXYZ/app-ios-project/en_devel",
"method": "source"

{
  "error": {
    "type": "server_error",
    "http_status": 500,
    "message": "Internal Server Error",
    "details": [
      {
        "code": "error",
        "detail": "Server Error (500)",
        "attr": null
      }
    ]
  },
  "upload": {
    "status": "❌ Failed to upload en.xliff",
    "file": "en.xliff",
    "input_path": "_Translations/en.xliff",
    "component": "companyXYZ/app-ios-project/en_devel",
    "method": "source"
  },
  "command": [
    "wlc",
    "--url", "https://weblate.companyXYZ.com/api/",
    "--key", "wlu_abcdefg1234567890abcdefg",
    "upload",
    "companyXYZ/app-ios-project/en_devel",
    "--input", "_Translations/en.xliff",
    "--method", "source"
  ],
  "exit_status": 1
}

"component": "companyXYZ/app-ios-project/en_devel",
"method": "replace"

{
  "error": {
    "type": "server_error",
    "http_status": 500,
    "message": "Internal Server Error",
    "details": [
      {
        "code": "error",
        "detail": "Server Error (500)",
        "attr": null
      }
    ]
  },
  "upload": {
    "status": "❌ Failed to upload en.xliff",
    "file": "en.xliff",
    "input_path": "_Translations/en.xliff",
    "component": "companyXYZ/app-ios-project/en_devel",
    "method": "replace"
  },
  "command": [
    "wlc",
    "--url", "https://weblate.companyXYZ.com/api/",
    "--key", "wlu_abcdefg1234567890abcdefg",
    "upload",
    "companyXYZ/app-ios-project/en_devel",
    "--input", "_Translations/en.xliff",
    "--method", "replace"
  ],
  "exit_status": 1
}

[nijel]

Can you check server logs what is the actual error there?

[ddeveloperuch]

@nijel please let me know if further details would be helpful, I’m happy to share anything that might assist in resolving the issue.

[ddeveloperuch]

@nijel I noticed that the English (Developer) language, which is used as the source for strings, does not provide UI option to upload translations. I suspect this limitation might be related to the HTTP 500 Server Error that occurs when attempting to replace English (Developer) strings using the wlc tool with the --method source \ --method replace options.

[ddeveloperuch]

@nijel Can you check server logs what is the actual error there?

@nijel It was a good suggestion to check the server logs, and here are the results of our investigation.
We’re currently running Weblate 5.12.2, with wlc version 1.15. Below is the relevant output from the logs with debug mode enabled:

gunicorn stderr | Internal Server Error: /api/translations/companyXYZ/app-ios-project/en_devel/file/
gunicorn stderr | Traceback (most recent call last):
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/django/core/handlers/exception.py", line 55, in inner
gunicorn stderr |     response = get_response(request)
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/django/core/handlers/base.py", line 197, in _get_response
gunicorn stderr |     response = wrapped_callback(request, *callback_args, **callback_kwargs)
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/django/views/decorators/csrf.py", line 65, in _view_wrapper
gunicorn stderr |     return view_func(request, *args, **kwargs)
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/rest_framework/viewsets.py", line 125, in view
gunicorn stderr |     return self.dispatch(request, *args, **kwargs)
gunicorn stderr |            ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/rest_framework/views.py", line 515, in dispatch
gunicorn stderr |     response = self.handle_exception(exc)
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/rest_framework/views.py", line 475, in handle_exception
gunicorn stderr |     self.raise_uncaught_exception(exc)
gunicorn stderr |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/rest_framework/views.py", line 486, in raise_uncaught_exception
gunicorn stderr |     raise exc
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/rest_framework/views.py", line 512, in dispatch
gunicorn stderr |     response = handler(request, *args, **kwargs)
gunicorn stderr |   File "/app/venv/lib/python3.13/site-packages/weblate/api/views.py", line 1677, in file
gunicorn stderr |     self.permission_denied(request, can_upload.reason)
gunicorn stderr |                                     ^^^^^^^^^^^^^^^^^
gunicorn stderr | AttributeError: 'bool' object has no attribute 'reason'
nginx stdout | 109.43.50.12 - - [23/Jul/2025:07:29:15 +0000] "POST /api/translations/companyXYZ/app-ios-project/en_devel/file/ HTTP/1.0" 500 44428 "-" "wlc/1.15"

We noticed the line: self.permission_denied(request, can_upload.reason), this appears to raise an AttributeError because can_upload is a bool, not an object with a reason attribute.

Initially, we suspected this might be a permission issue. However, we’ve double-checked the API token and account permissions. I have admin access, and we also tested with a super admin account and a project token, but the issue persists in all cases.
We also tried downgrading our Weblate instance to 5.11.1, but the exact same error occurred.
I hope this information helps in identifying the root cause. Please let me know if there’s anything else I can provide to assist further. Thank you!

[nijel]

It is indeed permission error, but the denied handling is broken for some corner cases, #15596 fixes that.

[ddeveloperuch]

It’s great to hear that the issue we encountered turned out to be a real bug. We’re happy to have contributed to improving the Weblate platform. Thank you, @nijel, for the quick fix, we’ll be looking forward to the release of version 5.13 or a possible patch in 5.12.3.

[ddeveloperuch]

@nijel Hello Michal, I understand this is quite a tricky issue. I’m just wondering if you might have missed my last detailed reply about the problem and whether you’ve had a chance to take a look?

[nijel]

I just didn't yet get to it. If you need faster support, we have (paid) options for that; check it out at https://weblate.org/support/.

[ddeveloperuch]

@nijel Thank you for letting know. There’s nothing urgent on our side, so we’re happy to wait for your expert solution.