mozilla/pdf.js · error · FormatError

Invalid crypt filter name.

Error message

Invalid crypt filter name.

What it means

FormatError thrown inside the per-object cipher resolver (used for V=4/V=5 documents) when the crypt filter name passed in is not a PDF Name object. The StmF/StrF entries in the Encrypt dict must reference crypt filters by Name; if they resolve to something else (string, number, null), the resolver cannot look up the filter.

Source

Thrown at src/core/crypto.js:1287

      password
    );
    this.encryptionKey = transform.encryptionKey;
  }

  /**
   * @param {number} num
   *   Object number.
   * @param {number} gen
   *   Generation number.
   * @returns {CipherTransform}
   *   Cipher transform.
   */
  createCipherTransform(num, gen) {
    if (this.algorithm === 4 || this.algorithm === 5) {
      /** @type {ResolveCipher} */
      const resolveCipher = filterName => {
        if (!(filterName instanceof Name)) {
          throw new FormatError("Invalid crypt filter name.");
        }
        const cryptFilter = this.cf.get(filterName.name);
        const cfm = cryptFilter?.get("CFM");

        if (!cfm || cfm.name === "None") {
          return NullCipher;
        }
        if (!this.encryptionKey) {
          throw new PasswordException(
            "No password given",
            PasswordResponses.NEED_PASSWORD
          );
        }
        if (this.algorithm === 5 || cfm.name === "AESV3") {
          // V=5 always uses 256-bit AES with the file encryption key, even
          // when a producer wrongly sets the crypt filter's CFM to AESV2
          // (bug 2046659).
          return AES256Cipher.bind(null, this.encryptionKey);

View on GitHub (pinned to 5903d58d58)

Solutions

1. Re-save the PDF with a conformant producer so StmF/StrF are Names.
2. If you must handle such files, pre-process the Encrypt dict to coerce string-valued StmF/StrF to Names (advanced, requires xref access).
3. Surface a 'corrupt crypt filter configuration' message to the user.

try {
  const doc = await getDocument({ url }).promise;
} catch (e) {
  if (e.name === 'FormatError' && e.message === 'Invalid crypt filter name.') {
    notifyUser('The PDF has a corrupt crypt filter configuration and cannot be opened.');
    return;
  }
  throw e;
}

When it happens

Trigger: A V=4/V=5 Encrypt dict whose StmF or StrF entry is a string literal or other non-Name type; an indirect reference that resolved to a non-Name; a malformed CF lookup triggered when decrypting a stream or string object.

Common situations: Buggy producers that emit StmF as a string instead of a name; corrupt Encrypt dict; rarely hit because most producers emit Names correctly.

Related errors

• Unknown crypto method
• unknown encryption method
• unsupported encryption algorithm
• invalid key length
• No password given

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/b7d4c03448b23c26. Report an issue: GitHub.