reflex-dev/reflex · error · ValueError

app_name should be a string

Error message

app_name should be a string

What it means

Raised by create_app() when app_name is not a non-empty string. The name becomes the 'name' field of the POST /api/v1/apps payload, so the library validates it up front rather than letting the backend reject the request. Typically hit when passing None, an empty string, or a non-str value from config or CLI options.

Source

Thrown at packages/reflex-hosting-cli/src/reflex_cli/utils/hosting.py:956

        app_name: The name of the application.
        description: The description of the application.
        project_id: The ID of the project to associate the application with.
        client: The authenticated client
        provider: The hosting provider to pin the app to (e.g. "gcp"). ``None``
            keeps the Reflex Cloud default.

    Returns:
        dict: The created application details as a dictionary.

    Raises:
        NotAuthenticatedError: If the token is not valid.
        ValueError: If forbidden.

    """
    import httpx

    if not isinstance(app_name, str) or not app_name:
        raise ValueError("app_name should be a string")
    if not isinstance(client, AuthenticatedClient):
        raise NotAuthenticatedError("not authenticated")
    payload: dict[str, Any] = {
        "name": app_name,
        "description": description,
        "project": project_id,
    }
    if provider is not None:
        payload["provider"] = provider
    response = httpx.post(
        urljoin(constants.Hosting.HOSTING_SERVICE, "/api/v1/apps/"),
        json=payload,
        headers=authorization_header(client.token),
        timeout=constants.Hosting.TIMEOUT,
    )
    if response.status_code == HTTPStatus.FORBIDDEN:
        logger.debug(f"Server responded with 403: {response.text}")
        raise ValueError(f"{response.text}")

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Set a valid non-empty string app name in rxconfig.yaml (app_name = "my-app") or pass it explicitly to create_app()
2. Check the value is truthy before deploying: assert isinstance(app_name, str) and app_name
3. If the name comes from user input, strip and validate it before calling create_app

Example fix

# before
app = create_app(client, app_name=None, project_id=proj_id)

# after
app_name = config.app_name or "my-default-app"
app = create_app(client, app_name=app_name, project_id=proj_id)

app_name = (app_name or config.app_name or "").strip()
if not app_name:
    raise ValueError("app_name is required before deploy")
create_app(client, app_name=app_name, project_id=project_id)

def is_valid_app_name(name: object) -> bool:
    return isinstance(name, str) and bool(name.strip())

try:
    create_app(client, app_name, project_id)
except ValueError as ex:
    if "app_name" in str(ex):
        app_name = config.app_name
        create_app(client, app_name, project_id)
    else:
        raise

When it happens

Trigger: Calling create_app() (used by deploy and directly in tests) with app_name=None, "", or a non-string — e.g. reading rxconfig.yaml's app_name into the wrong variable, or a CLI flag left unset.

Common situations: rxconfig.yaml has a missing/empty app_name; scripted deploy passes a falsy name; refactoring renamed the variable holding the name.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• app_id should be a string
• bad hostname provided
• project search failed: {ex_details}
• detail
• deployment failed: {ex_details}

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/0791639cbcf80efa. Report an issue: GitHub.