reflex-dev/reflex · error · FileNotFoundError

The stylesheet file {stylesheet_full_path} does not exist.

Error message

The stylesheet file {stylesheet_full_path} does not exist.

What it means

Each non-URL stylesheet listed in add_styles must exist under the app's assets directory at compile time; Reflex needs to read (and for directories, rglob) the file(s) to inline them into the compiled root stylesheet. A missing file raises FileNotFoundError.

Source

Thrown at reflex/compiler/compiler.py:365

    active_plugins = get_config().plugins if plugins is None else plugins
    sheets.extend([
        sheet for plugin in active_plugins for sheet in plugin.get_stylesheet_paths()
    ])

    failed_to_import_sass = False
    assets_app_path = Path.cwd() / constants.Dirs.APP_ASSETS

    stylesheets_files: list[Path] = []
    stylesheets_urls = []

    for stylesheet in stylesheets:
        if not utils.is_valid_url(stylesheet):
            # check if stylesheet provided exists.
            stylesheet_full_path = assets_app_path / stylesheet.strip("/")

            if not stylesheet_full_path.exists():
                msg = f"The stylesheet file {stylesheet_full_path} does not exist."
                raise FileNotFoundError(msg)

            if stylesheet_full_path.is_dir():
                all_files = (
                    file
                    for ext in constants.Reflex.STYLESHEETS_SUPPORTED
                    for file in stylesheet_full_path.rglob("*." + ext)
                )
                for file in all_files:
                    if file.is_dir():
                        continue
                    # Validate the stylesheet.
                    _validate_stylesheet(file, assets_app_path)
                    stylesheets_files.append(file)

            else:
                # Validate the stylesheet.
                _validate_stylesheet(stylesheet_full_path, assets_app_path)
                stylesheets_files.append(stylesheet_full_path)

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Create or commit the file at the exact path shown in the error message
2. Correct the path/subdirectory in the add_styles entry
3. Check .gitignore rules if the file exists locally but fails in CI/other checkouts

Example fix

# before
app = rx.App(add_styles=["/css/theme.css"])  # file actually at assets/styles/theme.css
# after
app = rx.App(add_styles=["/styles/theme.css"])

from pathlib import Path

def validate_stylesheet_files(styles: list[str], assets_dir: Path) -> list[str]:
    for s in styles:
        if s.startswith(("http://", "https://")):
            continue
        p = assets_dir / s.strip("/")
        if not p.exists():
            raise FileNotFoundError(f"stylesheet not found: {p}")
    return styles

app = rx.App(add_styles=validate_stylesheet_files(my_styles, Path(".web/assets")))

When it happens

Trigger: rx.App(add_styles=["/css/theme.css"]) where assets/css/theme.css does not exist — typo'd name, wrong subdirectory, or file never committed. Also triggered when a directory entry matches no supported stylesheet files inside it.

Common situations: Renaming/moving CSS files without updating App config; assets excluded by .gitignore so teammates/CI hit it; case-mismatch of the filename across operating systems.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• Stylesheet file {stylesheet_full_path} is not supported.
• Cannot include stylesheets from outside the assets directory
• Stylesheet file name cannot be '{PageNames.STYLESHEET_ROOT}'
• File not found: {src_file_local}
• Stylesheet file name cannot be empty: {stylesheet_full_path}

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/d12982bf8460e28b. Report an issue: GitHub.