nautechsystems/nautilus_trader · error · ValueError

Theme name cannot be empty

Error message

Theme name cannot be empty

What it means

register_theme refuses blank names (name.strip() falsy) after its three None checks on name/template/colors. An empty theme name could never be selected via get_theme from configs, so it is rejected at registration time.

Source

Thrown at python/nautilus_trader/analysis/themes.py:173

    ...     "custom",
    ...     "plotly_white",
    ...     {
    ...         "primary": "#ff6600",
    ...         "positive": "#00ff00",
    ...         "negative": "#ff0000",
    ...         "neutral": "#808080",
    ...         "background": "#ffffff",
    ...         "grid": "#dddddd",
    ...     },
    ... )

    """
    _require_not_none(name, "name")
    _require_not_none(template, "template")
    _require_not_none(colors, "colors")

    if not name.strip():
        raise ValueError("Theme name cannot be empty")

    required_keys = {"primary", "positive", "negative", "neutral", "background", "grid"}
    missing_keys = required_keys - set(colors.keys())
    if missing_keys:
        raise ValueError(
            f"Colors dict missing required keys: {missing_keys}. Required keys: {required_keys}",
        )

    _THEMES[name] = {
        "template": template,
        "colors": colors.copy(),
    }


def list_themes() -> list[str]:
    """
    List all registered theme names.

View on GitHub (pinned to a4b06ed870)

Solutions

1. Register with a real name: register_theme('corp-brand', 'plotly_white', colors)
2. Sanitize before registering: name = raw.strip(); if not name: raise/skip

Example fix

# before
register_theme('', 'plotly_white', colors)
# ValueError: Theme name cannot be empty

# after
register_theme('corp-brand', 'plotly_white', colors)

name = (name or '').strip()
if not name:
    raise ValueError('Theme name required')
register_theme(name, template, colors)

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

When it happens

Trigger: register_theme('', template, colors) or register_theme(' ', ...) — e.g. a name variable built from empty user input or a config key that was never populated.

Common situations: Theme registration loops driven by a config dict; names sourced from filenames/IDs that can be blank.

Related errors

• Colors dict missing required keys: {missing_keys}. Required
• {name} must not be None
• Theme '{name}' not found.{suggestion_text} Available themes:
• No tearsheet chart registered under '{chart_name}'.{hint} Re
• Chart renderer must be callable, was {type(renderer)}

AI-assisted analysis of nautechsystems/nautilus_trader@a4b06ed870 (2026-08-16). Data as JSON: /api/errors/dc52b7ae6870a56a. Report an issue: GitHub.