langgenius/dify · error

The server does not support the media type transmitted in th

Error message

The server does not support the media type transmitted in the request.

What it means

Flask `abort(415)` (HTTP 415 Unsupported Media Type) at api/controllers/console/app/workflow.py:637 in the sync-draft-workflow POST handler. The handler accepts only `application/json` (parsed via `request.get_json`) or `text/plain` (raw JSON body validated with `model_validate_json`). Any other Content-Type falls through to the `else: abort(415)` branch. The default werkzeug 415 message is 'The server does not support the media type transmitted in the request.'

Source

Thrown at api/controllers/console/app/workflow.py:637

    @rbac_permission_required(RBACResourceScope.APP, RBACPermission.APP_VIEW_LAYOUT)
    def post(self, current_user: Account, app_model: App):
        """
        Sync draft workflow
        """
        content_type = request.headers.get("Content-Type", "")

        if "application/json" in content_type:
            payload_data = request.get_json(silent=True)
            if not isinstance(payload_data, dict):
                return {"message": "Invalid JSON data"}, 400
            args_model = SyncDraftWorkflowPayload.model_validate(payload_data)
        elif "text/plain" in content_type:
            try:
                args_model = SyncDraftWorkflowPayload.model_validate_json(request.data)
            except (ValueError, ValidationError):
                return {"message": "Invalid JSON data"}, 400
        else:
            abort(415)
        workflow_service = WorkflowService()

        try:
            environment_variable_patch = args_model.environment_variable_patch
            environment_variable_upserts: list[VariableBase] | None = None
            deleted_environment_variable_ids: list[str] = []
            if environment_variable_patch is not None:
                environment_variable_upsert_mappings = Workflow.normalize_environment_variable_mappings(
                    environment_variable_patch.environment_variables,
                )
                environment_variable_upserts = [
                    variable_factory.build_environment_variable_from_mapping(obj)
                    for obj in environment_variable_upsert_mappings
                ]
                deleted_environment_variable_ids = environment_variable_patch.deleted_environment_variable_ids
            conversation_variables = [
                variable_factory.build_conversation_variable_from_mapping(obj)
                for obj in args_model.conversation_variables

View on GitHub (pinned to ef8544b173)

Solutions

1. Set `Content-Type: application/json` and send a JSON object body.
2. If sending a raw JSON string, use `Content-Type: text/plain`.
3. Do not use multipart/form-data or form-urlencoded for this endpoint.

Example fix

// before
fetch(url, { method: 'POST', body: formData })
// after
fetch(url, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify(payload),
})

ct = (headers or {}).get("Content-Type", "")
if "application/json" not in ct and "text/plain" not in ct:
    raise ValueError("Content-Type must be application/json or text/plain")
# then ensure the body matches the chosen type

def is_supported_workflow_content_type(value: str) -> bool:
    v = (value or "").lower()
    return "application/json" in v or "text/plain" in v

try:
    resp = client.post(f"/console/api/apps/{app_id}/workflows/draft", headers=h, data=body)
except HTTPError as err:
    if err.response.status_code == 415:
        raise TypeError("set Content-Type to application/json for the sync-draft endpoint") from err
    raise

When it happens

Trigger: POSTing to `/apps/<app_id>/workflows/draft` with a Content-Type header other than `application/json` or `text/plain` — e.g. `multipart/form-data`, `application/x-www-form-urlencoded`, or no Content-Type at all.

Common situations: Client sets Content-Type to `application/json; charset=utf-8` is fine (substring match), but a fetch with `FormData`, a missing header, or a typo like `application/jason` triggers 415.

Related errors

• usage_missing_arg
• patched environment variables require an id
• patched environment variable ids must be unique
• deleted environment variable ids must not be empty
• deleted environment variable ids must be unique

AI-assisted analysis of langgenius/dify@ef8544b173 (2026-08-12). Data as JSON: /api/errors/15790f5b63cd1a23. Report an issue: GitHub.