withastro/astro · error · AstroError

CannotDetermineWeightAndStyleFromFontFile

CannotDetermineWeightAndStyleFromFontFile

Error message

An error occurred while determining the `weight` and `style` from local family "${family}" font file: ${url}.

What it means

Thrown by FontaceFontFileReader.extract when the fontace library cannot parse a local font file to derive its weight and style. The reader does a synchronous readFileSync(url) and passes the buffer to fontace; if fontace throws (corrupt or unrecognized font), the error is wrapped as CannotDetermineWeightAndStyleFromFontFile with the family and url.

Source

Thrown at packages/astro/src/assets/fonts/infra/fontace-font-file-reader.ts:16

import { readFileSync } from 'node:fs';
import { fontace } from 'fontace';
import { AstroError, AstroErrorData } from '../../../core/errors/index.js';
import type { FontFileReader } from '../definitions.js';
import type { Style } from '../types.js';

export class FontaceFontFileReader implements FontFileReader {
	extract({ family, url }: { family: string; url: string }): { weight: string; style: Style } {
		try {
			const data = fontace(readFileSync(url));
			return {
				weight: data.weight,
				style: data.style as Style,
			};
		} catch (cause) {
			throw new AstroError(
				{
					...AstroErrorData.CannotDetermineWeightAndStyleFromFontFile,
					message: AstroErrorData.CannotDetermineWeightAndStyleFromFontFile.message(family, url),
				},
				{ cause },
			);
		}
	}
}

View on GitHub (pinned to d081033d5f)

Solutions

1. Confirm the file at url is a valid, complete font (open it in a font tool or re-download).
2. Verify the path is correct and points to the intended .woff/.woff2/.ttf/.otf file.
3. Provide explicit weight and style in the font config so extraction is not required.
4. Re-download the font from the original source to rule out truncation.
5. Inspect the `cause` to see fontace's specific parse error.

Example fix

// before
{ family: 'MyFont', src: [local('MyFont')] }

// after - specify weight/style explicitly to bypass extraction
{ family: 'MyFont', weight: 700, style: 'normal', src: [local('MyFont-Bold')] }

import { existsSync, statSync } from 'node:fs';
function isValidLocalFont(url: string): boolean {
  return existsSync(url) && statSync(url).size > 0;
}

try { reader.extract({ family, url }); }
catch (e) {
  if (e instanceof AstroError && e.code === 'CannotDetermineWeightAndStyleFromFontFile') {
    // fall back to explicit weight/style from config
  }
}

When it happens

Trigger: Calling extract({ family, url }) on a local font file that is not a valid parseable font (e.g. a .txt renamed to .woff2), a truncated/corrupt binary, or an unsupported font container that fontace cannot introspect. Also thrown if readFileSync itself fails before fontace runs.

Common situations: User points a local() source at the wrong file, a font downloaded incompletely, a license/placeholder file, or a font format fontace does not yet support. Typically surfaces during astro build while resolving local families.

Related errors

• UnknownFilesystemError
• UnknownFilesystemError
• CannotFetchFontFile
• CannotExtractFontType
• UnknownFilesystemError

AI-assisted analysis of withastro/astro@d081033d5f (2026-08-12). Data as JSON: /api/errors/cfbf053143ced1d0. Report an issue: GitHub.