mozilla/pdf.js · error · Error

Built-in CMap parameters are not provided.

Error message

Built-in CMap parameters are not provided.

What it means

Thrown by createBuiltInCMap when the fetchBuiltInCMap argument is falsy. The library needs a callback to load the binary .bcmap files for any non-Identity built-in CMap; without it, resolving a Name-encoded CMap is impossible. Usually the evaluator supplies this callback, but only when cMapUrl is configured.

Source

Thrown at src/core/cmap.js:682

    if (!cMap.contains(key)) {
      cMap.mapOne(key, value);
    }
  });

  return cMap;
}

async function createBuiltInCMap(name, fetchBuiltInCMap) {
  if (name === "Identity-H") {
    return new IdentityCMap(false, 2);
  } else if (name === "Identity-V") {
    return new IdentityCMap(true, 2);
  }
  if (!BUILT_IN_CMAPS.includes(name)) {
    throw new Error("Unknown CMap name: " + name);
  }
  if (!fetchBuiltInCMap) {
    throw new Error("Built-in CMap parameters are not provided.");
  }

  const { cMapData, isCompressed } = await fetchBuiltInCMap(name);
  const cMap = new CMap(true);

  if (isCompressed) {
    return new BinaryCMapReader().process(cMapData, cMap, useCMap =>
      extendCMap(cMap, fetchBuiltInCMap, useCMap)
    );
  }
  const lexer = new Lexer(new Stream(cMapData));
  return parseCMap(cMap, lexer, fetchBuiltInCMap, null);
}

class CMapFactory {
  static async create({ encoding, fetchBuiltInCMap, useCMap }) {
    if (encoding instanceof Name) {
      return createBuiltInCMap(encoding.name, fetchBuiltInCMap);

View on GitHub (pinned to 5903d58d58)

Solutions

1. Pass cMapUrl and cMapPacked: true to getDocument, pointing at the bundled cmaps/ directory from pdfjs-dist.
2. If using a custom worker setup, supply a fetchBuiltInCMap(name) callback returning { cMapData: ArrayBuffer, isCompressed: boolean }.
3. For node, install pdfjs-dist and point cMapUrl at its cmaps/ folder (e.g. node_modules/pdfjs-dist/cmaps/).

Example fix

// before
getDocument({ url }); // no CMap config -> CJK fonts fail

// after
getDocument({
  url,
  cMapUrl: '/node_modules/pdfjs-dist/cmaps/',
  cMapPacked: true,
});

// Ensure a fetcher is configured before loading a CMap-dependent PDF
function buildFetchBuiltInCMap(cMapUrl, cMapPacked) {
  if (!cMapUrl) return null;
  return async (name) => {
    const suffix = cMapPacked ? '.bcmap' : '';
    const cMapData = await fetch(`${cMapUrl}${name}${suffix}`).then(r => r.arrayBuffer());
    return { cMapData, isCompressed: cMapPacked };
  };
}

function hasCMapFetcher(opts) {
  return typeof opts.fetchBuiltInCMap === 'function'
    || (typeof opts.cMapUrl === 'string' && opts.cMapUrl.length > 0);
}

When it happens

Trigger: Calling CMapFactory.create({ encoding: Name, fetchBuiltInCMap: null }) directly, or running the worker without cMapUrl configured so PartialEvaluator never builds a fetcher and passes undefined through.

Common situations: Embedding pdf.js without setting cMapUrl/cMapPacked in getDocument; node.js usage that constructs the evaluator manually; a stripped-down build that omits the standard CMap loading path.

Related errors

• Unknown CMap name: ${name}
• Max size of CID is 65,535
• mapCidRange - ignoring data above MAX_MAP_RANGE.
• mapBfRange - ignoring data above MAX_MAP_RANGE.
• mapBfRangeToArray - ignoring data above MAX_MAP_RANGE.

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/1a4802074ef69c58. Report an issue: GitHub.