mozilla/pdf.js · error · Error

Ensure that the `${kind}` API parameter is provided.

Error message

Ensure that the `${kind}` API parameter is provided.

What it means

Thrown by BaseBinaryDataFactory.fetch({ kind, filename }) when this[kind] is falsy, i.e., the corresponding configuration parameter was not supplied. The factory is used internally to load CMap binary files (cMapUrl), standard font metrics (standardFontDataUrl), and WASM decoders such as OpenJPEG (wasmUrl). Without a base URL there is no place to fetch the resource from.

Source

Thrown at src/display/binary_data_factory.js:49

      unreachable("Cannot initialize BaseBinaryDataFactory.");
    }
    this.cMapUrl = cMapUrl;
    this.standardFontDataUrl = standardFontDataUrl;
    this.wasmUrl = wasmUrl;
  }

  async fetch({ kind, filename }) {
    switch (kind) {
      case "cMapUrl":
      case "standardFontDataUrl":
      case "wasmUrl":
        break;
      default:
        unreachable(`Not implemented: ${kind}`);
    }
    const baseUrl = this[kind];
    if (!baseUrl) {
      throw new Error(`Ensure that the \`${kind}\` API parameter is provided.`);
    }
    const url = `${baseUrl}${filename}`;

    return this._fetch(url, kind).catch(reason => {
      throw new Error(`Unable to load ${this.#errorStr[kind]} data at: ${url}`);
    });
  }

  /**
   * @ignore
   * @returns {Promise<Uint8Array>}
   */
  async _fetch(url, kind) {
    unreachable("Abstract method `_fetch` called.");
  }
}

class DOMBinaryDataFactory extends BaseBinaryDataFactory {

View on GitHub (pinned to 5903d58d58)

Solutions

1. Install pdfjs-dist's cmaps and standard fonts assets and point cMapUrl / standardFontDataUrl at them (with trailing '/').
2. If you ship JPEG2000 support, set wasmUrl to the folder containing the openjpeg wasm.
3. Confirm the URLs resolve over HTTP (200) before relying on them.

Example fix

// before
getDocument({ data });

// after
getDocument({
  data,
  cMapUrl: 'https://cdn.example.com/cmaps/',
  standardFontDataUrl: 'https://cdn.example.com/standard_fonts/',
});

function validatePdfjsConfig(cfg) {
  const needed = [];
  if (cfg.useCMaps && !cfg.cMapUrl) needed.push('cMapUrl');
  if (!cfg.standardFontDataUrl) needed.push('standardFontDataUrl');
  if (needed.length) throw new Error('Missing pdfjs config: ' + needed.join(', '));
}
validatePdfjsConfig(config);

null

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When it happens

Trigger: Loading a CJK PDF without configuring cMapUrl; a PDF using a non-embedded standard font without standardFontDataUrl; a JPEG2000 image when openjpeg WASM is required but wasmUrl is unset.

Common situations: Self-hosting pdfjs-dist and forgetting the /cmaps/ and /standard_fonts/ asset folders; bundle configs that tree-shake the wasmUrl; moving from the legacy build (which had bundled bcmaps) to the modular one.

Related errors

• Invalid factory url: "${val}" must include trailing slash.
• No ICC color space support
• JBig2 failed to initialize
• Unable to load ${this.#errorStr[kind]} data at: ${url}
• response.statusText

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/5b143c3485b9bff6. Report an issue: GitHub.