mozilla/pdf.js · error · Error

Not enough arguments in printf

Error message

Not enough arguments in printf

What it means

Thrown by `Util.printf()` (src/scripting_api/util.js:101) during the format-string scan. After matching each valid conversion specifier (`%d %f %s %x`), it advances an argument cursor `i`; if the cursor runs past the last supplied argument, there are more specifiers than values and it throws. Non-conversion characters (e.g. `%a`) are passed through without consuming an argument.

Source

Thrown at src/scripting_api/util.js:101

        // cConvChar must be one of d, f, s, x
        if (
          cConvChar !== "d" &&
          cConvChar !== "f" &&
          cConvChar !== "s" &&
          cConvChar !== "x"
        ) {
          const buf = ["%"];
          for (const str of [nDecSep, cFlags, nWidth, nPrecision, cConvChar]) {
            if (str) {
              buf.push(str);
            }
          }
          return buf.join("");
        }

        i++;
        if (i === args.length) {
          throw new Error("Not enough arguments in printf");
        }
        const arg = args[i];

        if (cConvChar === "s") {
          return arg.toString();
        }

        let flags = 0;
        if (cFlags) {
          for (const flag of cFlags) {
            switch (flag) {
              case "+":
                flags |= PLUS;
                break;
              case " ":
                flags |= SPACE;
                break;
              case "0":

View on GitHub (pinned to 5903d58d58)

Solutions

1. Align the number of conversion specifiers with the supplied values; count `%d|%f|%s|%x` in the format and pad the values.
2. Use `%s` with `.toString()` and pass explicit placeholders for missing values.
3. Build the format string programmatically from the value count so the two can never drift.

Example fix

// before
util.printf('%s %s %s', a, b); // missing third value
// after
util.printf('%s %s %s', a, b, c ?? '');

function printfSafe(util, fmt, ...values) {
  const specifiers = (fmt.match(/%[dfsx]/g) || []).length;
  while (values.length < specifiers) values.push('');
  return util.printf(fmt, ...values);
}

function specifierCountsMatch(fmt, values) {
  const specifiers = (String(fmt).match(/%[dfsx]/g) || []).length;
  return Array.isArray(values) && values.length >= specifiers;
}

When it happens

Trigger: Calling `util.printf('%s %s', 'onlyOne')`, `util.printf('%d/%d/%d', year, month)` (missing the third), or a format string whose specifiers were extended after the values were fixed.

Common situations: Localizing a format string that added a specifier the original values did not provide; templating date/number strings where the caller passes fewer fields than the template expects.

Related errors

• Invalid number of params in printf
• First argument of printf must be a string
• Invalid rotation: must be a multiple of 90
• app.activeDocs is read-only
• app.constants is read-only

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/94dfe7a7b50b126c. Report an issue: GitHub.