Just tried this:

As soon as the Lastpass vault opens itself, I closed the tab. This prevented the extension from breaking. Then, when I opened the vault myself, the extension again broke.

Same issue here. Lastpass extension was installed and working fine until my chromebook updated to 61.0.3163.51 beta 32-bit this morning.Now I have the exact same issue as the OP.

Chrome version: 61.0.3163.51 beta 32-bit
Device: ASUS C100P

About 90% of the newer reviews for the extension are now about this problem: https://chrome.google.com/webstore/detail/lastpass-free-password-ma/hdokiejnpimakedhajhdlcegeplioahd/reviews  A lot of users seem to experience this.

The Lastpass people now fixed this, but the problem is still occuring in other extensions. And I found the culprit:

* Say you have a file in the extension, script.js.
* And in an HTML file, embed the script, but with a different upper/lower case spelling than the actual file has.  E.g.: <script src='sCript.js'></script>
* Now when the HTML file is opened, on MS Windows everything is fine. But on my Chromebook the extension breaks. This occurs only, when the extension has been added from the store, not for unpackaged extensions.

Here's a simple way to test this, with any extension:

Open the developer console for any extension page, and there run the following code:

function addScript( src ) {
  var s = document.createElement( 'script' );
  s.setAttribute( 'src', src );
  document.body.appendChild( s );
}

function flipCase (s) {return s.split('').map(function(c) {
  return (c === c.toUpperCase()) ? c.toLowerCase() : c.toUpperCase();
}).join('');}

addScript(flipCase(document.URL));

Duplicate of issue 834794