langgenius/dify · error · ValueError

Invalid filters

Error message

Invalid filters

What it means

Bare ValueError('Invalid filters') raised inside DefaultBlockConfigApi.get (GET /apps/{app_id}/workflows/default-workflow-block-configs/{block_type}) when the 'q' query string is present but fails json.loads (json.JSONDecodeError). The value is forwarded as filters to WorkflowService.get_default_block_config. The ValueError propagates as HTTP 400 'Invalid filters'.

Source

Thrown at api/controllers/console/app/workflow.py:1390

    @console_ns.doc(params=query_params_from_model(DefaultBlockConfigQuery))
    @setup_required
    @login_required
    @account_initialization_required
    @edit_permission_required
    @rbac_permission_required(RBACResourceScope.APP, RBACPermission.APP_VIEW_LAYOUT)
    @get_app_model(mode=[AppMode.ADVANCED_CHAT, AppMode.WORKFLOW])
    def get(self, app_model: App, block_type: str):
        """
        Get default block config
        """
        args = DefaultBlockConfigQuery.model_validate(request.args.to_dict(flat=True))

        filters = None
        if args.q:
            try:
                filters = json.loads(args.q)
            except json.JSONDecodeError:
                raise ValueError("Invalid filters")

        # Get default block configs
        workflow_service = WorkflowService()
        return workflow_service.get_default_block_config(node_type=block_type, filters=filters)


@console_ns.route("/apps/<uuid:app_id>/convert-to-workflow")
class ConvertToWorkflowApi(Resource):
    @console_ns.expect(console_ns.models[ConvertToWorkflowPayload.__name__])
    @console_ns.doc("convert_to_workflow")
    @console_ns.doc(description="Convert application to workflow mode")
    @console_ns.doc(params={"app_id": "Application ID"})
    @console_ns.response(
        200,
        "Application converted to workflow successfully",
        console_ns.models[NewAppResponse.__name__],
    )
    @console_ns.response(400, "Application cannot be converted")

View on GitHub (pinned to ef8544b173)

Solutions

1. URL-encode a JSON.stringify-ed object for the q parameter, or omit it entirely.
2. Validate that q parses as JSON on the client before sending.
3. If no filter is needed, drop the q query parameter.

Example fix

// before: raw, un-encoded JSON in the URL
fetch(`/apps/${appId}/workflows/default-workflow-block-configs/llm?q={provider:openai}`)
// after: JSON.stringify + encodeURIComponent
const q = encodeURIComponent(JSON.stringify({provider:'openai'}));
fetch(`/apps/${appId}/workflows/default-workflow-block-configs/llm?q=${q}`)

// Validate q parses as JSON before sending; drop it if it doesn't.
let q;
try { q = rawQ ? JSON.parse(rawQ) : undefined; } catch { q = undefined; /* or show client error */ }
const url = `/console/apps/${appId}/workflows/default-workflow-block-configs/${blockType}` +
  (q ? `?q=${encodeURIComponent(JSON.stringify(q))}` : '');

const isJsonString = (s): boolean => { try { JSON.parse(s); return true; } catch { return false; } };

try {
  return await getDefaultBlockConfig(appId, blockType, q);
} catch (e) {
  if (e?.status === 400 && /Invalid filters/i.test(e?.message)) {
    // drop q and retry without filters
    return getDefaultBlockConfig(appId, blockType, undefined);
  }
  throw e;
}

When it happens

Trigger: Passing a malformed 'q' parameter that is not valid JSON, e.g. ?q=foo or ?q={bad, on the default-block-config endpoint.

Common situations: Frontend builds the q param by string concatenation instead of JSON.stringify; copy-pasted URL with truncated JSON; manual API testing with unencoded braces.

Related errors

• missing inputs
• Workflow not initialized
• source workflow must be published
• usage_missing_arg
• no_file_uploaded

AI-assisted analysis of langgenius/dify@ef8544b173 (2026-08-12). Data as JSON: /api/errors/c2b59843d093df90. Report an issue: GitHub.