mozilla/pdf.js · error · Error

doc.producer is read-only

Error message

doc.producer is read-only

What it means

`Doc.producer` returns the producer string from the PDF metadata (`this._producer`), populated when the document is parsed. It is a factual metadata attribute and read-only per the Acrobat spec — changing it would misrepresent the file's origin. PDF.js's throwing setter enforces that; scripts cannot overwrite the producer.

Source

Thrown at src/scripting_api/doc.js:607

  set path(_) {
    throw new Error("doc.path is read-only");
  }

  get permStatusReady() {
    return true;
  }

  set permStatusReady(_) {
    throw new Error("doc.permStatusReady is read-only");
  }

  get producer() {
    return this._producer;
  }

  set producer(_) {
    throw new Error("doc.producer is read-only");
  }

  get requiresFullSave() {
    return false;
  }

  set requiresFullSave(_) {
    throw new Error("doc.requiresFullSave is read-only");
  }

  get securityHandler() {
    return this._securityHandler;
  }

  set securityHandler(_) {
    throw new Error("doc.securityHandler is read-only");
  }

View on GitHub (pinned to 5903d58d58)

Solutions

  1. Remove the assignment; read `doc.producer` only (`var p = doc.producer;`).
  2. Perform metadata edits at the PDF-generation/processing layer (the producer is set by the creating application).
  3. Run legacy scripts through try/catch to tolerate the write attempt.

Example fix

// before
doc.producer = 'Custom Producer';

// after
var p = doc.producer; // read-only metadata
Defensive patterns

Strategy: validation

Validate before calling

const READ_ONLY_DOC_PROPS = new Set(['producer','subject','title','author','creator','keywords' /* ... */]);
function assertsNoReadOnlyWrite(scriptSrc) {
  for (const p of READ_ONLY_DOC_PROPS) {
    if (new RegExp(`\\bdoc\\.${p}\\s*=[^=]`).test(scriptSrc)) {
      throw new Error(`Script writes read-only property doc.${p}`);
    }
  }
}
assertsNoReadOnlyWrite(myScript);

Type guard

function isReadOnlyDocProp(doc, prop) {
  const desc = Object.getOwnPropertyDescriptor(Object.getPrototypeOf(doc), prop)
    || Object.getOwnPropertyDescriptor(doc, prop);
  return !!desc && !!desc.get && !desc.set;
}
isReadOnlyDocProp(doc, 'producer'); // true

Try / catch

try {
  doc.producer = 'Custom';
} catch (e) {
  if (/producer is read-only/.test(e.message)) console.warn(e.message);
  else throw e;
}

Prevention

When it happens

Trigger: A script writes `doc.producer = 'MyApp';` to brand or alter metadata. The setter throws on assignment.

Common situations: Scripts that try to rewrite metadata on save; branding workflows ported from Acrobat; code that assumes metadata setters exist.

Related errors

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/06aab14b19040882. Report an issue: GitHub.