File cannot read property of undefined

I get an error when trying to load this specific file into the webviewer. The file loads but the error prevents me from using javascript code I have later.

PDF.js Express Version
You can replicate the error on the demo page with this document

Detailed description of issue

Expected behaviour
File to load without error.

Does your issue happen with every document, or just one?
With just this specific document

Link to document
T183-20-SIGNING PAGE ONLY(6).pdf (87.9 KB)

Code snippet
Throws an error on load, it happens on the demo page of this website too.

Hello, I’m Ron, an automated tech support bot :robot:

While you wait for one of our customer support representatives to get back to you, please check out some of these documentation pages:


Hi Eric,

I am able to reproduce this issue in version 7.3.0 (the version currently for our demo). However, I am not able to reproduce the error in version 7.3.1+. Can you update your package and let me know if the problem persists?


In JavaScript almost everything is an object, null and undefined are exceptions. This error occurs when a property is read or a function is called on an undefined variable. Undefined means that a variable has been declared but has not been assigned a value. In JavaScript, properties and functions can only belong to objects. Since undefined is not an object type, calling a function or a property on such a variable causes the TypeError: Cannot read property of undefined.

If you are not sure a variable that will always have some value, the best practice is to check the value of variables for null or undefined before using them. To avoid getting these types of errors, you need to make sure that the variables you are trying to read do have the correct value. This can be done in various ways. You can do if checks before dealing with objects whose values are bound to change:

if (myVar !== undefined) {


if (typeof(myVar) !== 'undefined') {