withastro/astro · error · AstroError

FileParserNotFound

FileParserNotFound

Error message

No parser was found for '${fileName}'. Pass a parser function (e.g. `parser: csv`) to the `file` loader.

What it means

Thrown by the file() loader constructor when the fileName's extension is not one of the built-in supported types (json, yml, yaml, toml) and no custom parser function was supplied via options.parser. The loader needs a parser to convert file text into structured data and refuses to guess.

Source

Thrown at packages/astro/src/content/loaders/file.ts:46

	}

	let parse: ((text: string) => any) | null = null;

	const ext = fileName.split('.').at(-1);
	if (ext === 'json') {
		parse = JSON.parse;
	} else if (ext === 'yml' || ext === 'yaml') {
		parse = (text) =>
			yaml.load(text, {
				filename: fileName,
			});
	} else if (ext === 'toml') {
		parse = toml.parse;
	}
	if (options?.parser) parse = options.parser;

	if (parse === null) {
		throw new AstroError({
			...FileParserNotFound,
			message: FileParserNotFound.message(fileName),
		});
	}

	async function syncData(filePath: string, { logger, parseData, store, config }: LoaderContext) {
		let data: Array<Record<string, unknown>> | Record<string, Record<string, unknown>>;

		try {
			const contents = await fs.readFile(filePath, 'utf-8');
			data = await parse!(contents);
		} catch (error: any) {
			logger.error(`Error reading data from ${fileName}`);
			logger.debug(error.message);
			return;
		}

		const normalizedFilePath = posixRelative(fileURLToPath(config.root), filePath);

View on GitHub (pinned to d081033d5f)

Solutions

1. Provide a custom parser in the options: file('data.csv', { parser: (text) => parseCsv(text) }).
2. Convert your data to a supported format (json/yaml/toml) so the built-in parser applies.
3. Ensure the fileName has a recognizable extension and is spelled correctly.

Example fix

// before
defineCollection({ loader: file('data.csv') });
// after
import { parse as parseCsv } from 'csv-parse/sync';
defineCollection({
  loader: file('data.csv', { parser: (text) => parseCsv(text, { columns: true }) })
});

const BUILTIN_EXTS = new Set(['json','yml','yaml','toml']);
function ensureParser(fileName: string, parser?: Function) {
  const ext = fileName.split('.').at(-1);
  if (!parser && !BUILTIN_EXTS.has(ext ?? '')) {
    throw new Error(`No built-in parser for .${ext}; pass options.parser to file().`);
  }
}

const hasBuiltinParser = (ext?: string) => !!ext && ['json','yml','yaml','toml'].includes(ext);

When it happens

Trigger: Calling file('data.csv') or file('data.xml') without providing a parser option; calling file() on a file with no extension; a typo in the extension that doesn't match any built-in handler.

Common situations: Loading CSV, XML, TSV, or custom text formats without passing a parser; renaming a data file and forgetting to add a parser; new file formats the built-in set doesn't cover.

Related errors

• FileGlobNotSupported
• Glob patterns cannot start with `/`. Set the `base` option t
• Live content collections must be defined in "src/live.config
• Collection loader for ${name} does not have a load method
• ContentLoaderReturnsInvalidId

AI-assisted analysis of withastro/astro@d081033d5f (2026-08-12). Data as JSON: /api/errors/c16b487525174a5a. Report an issue: GitHub.