mozilla/pdf.js · error · FormatError

Malformed CMap: expected int.

Error message

Malformed CMap: expected int.

What it means

Thrown by the expectInt helper while parsing a CMap when the lexer yields a non-integer at a position that requires an integer token (for example the destination of a cidrange/cidchar entry). Indicates the CMap stream is structurally malformed.

Source

Thrown at src/core/cmap.js:458

}

function strToInt(str) {
  let a = 0;
  for (let i = 0; i < str.length; i++) {
    a = (a << 8) | str.charCodeAt(i);
  }
  return a >>> 0;
}

function expectString(obj) {
  if (typeof obj !== "string") {
    throw new FormatError("Malformed CMap: expected string.");
  }
}

function expectInt(obj) {
  if (!Number.isInteger(obj)) {
    throw new FormatError("Malformed CMap: expected int.");
  }
}

function parseBfChar(cMap, lexer) {
  while (true) {
    let obj = lexer.getObj();
    if (obj === EOF) {
      break;
    }
    if (isCmd(obj, "endbfchar")) {
      return;
    }
    expectString(obj);
    const src = strToInt(obj);
    obj = lexer.getObj();
    // TODO are /dstName used?
    expectString(obj);
    const dst = obj;

View on GitHub (pinned to 5903d58d58)

Solutions

1. Repair or regenerate the PDF.
2. Update pdf.js.
3. Catch FormatError and continue without that CMap (degrades CID text extraction).

try {
  await loadingTask.promise;
} catch (e) {
  if (e instanceof FormatError && /expected int/.test(e.message)) {
    console.warn('Malformed CMap (expected int), CID mapping may degrade', e);
  } else throw e;
}

When it happens

Trigger: Parsing a CMap where a token that must be an integer (CID destination, etc.) is a string, Name, Cmd, or float. Reached via parseCidChar / parseCidRange calling expectInt.

Common situations: Truncated or corrupt CID CMap; wrong stream referenced as a CMap; PDF produced by a faulty font tool.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• mapCidRange - ignoring data above MAX_MAP_RANGE.
• mapBfRange - ignoring data above MAX_MAP_RANGE.
• mapBfRangeToArray - ignoring data above MAX_MAP_RANGE.
• Malformed CMap: expected string.
• Invalid bf range.

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/29107a194ebb7054. Report an issue: GitHub.