# Google Chrome page speed extension causing error. How to fix?

**URL:** <https://forum.kirupa.com/t/google-chrome-page-speed-extension-causing-error-how-to-fix/326366>\
**Category:** random\
**Created:** [December 9, 2011, 3:54am UTC](https://forum.kirupa.com/t/google-chrome-page-speed-extension-causing-error-how-to-fix/326366 "2011-12-09T03:54:43Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![kadaj](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/kadaj/32/9061_2.png) [@kadaj](https://forum.kirupa.com/u/kadaj)\
**Post date:** [December 9, 2011, 3:54am UTC](https://forum.kirupa.com/t/google-chrome-page-speed-extension-causing-error-how-to-fix/326366/1 "2011-12-09T03:54:43Z")

</div>

Hi,  
A day ago, I updated Google Chrome dev channel build to the latest version. In my install dir I see two version, 17.0.963.0 and 17.0.963.2. The initial version ran page speed extension fine. But after an update, it’s causing this weird error. When I open the debugger tools, I get “Woops it looks like the DevTools Extensions API is unavailable from the remote browser”. I have attached a screenshot of the error below. The update took place automatically and told me to restart the browser. I want page speed extension working. If I disable the extension, this error no longer shows. Does anyone know how to fix this?  
My current version is 17.0.963.2 dev-m

![](http://forum.kirupa.com/uploads/kirupa/6599/403d317fab504bf8.png)  
//–end screenshot.

src: [fetch\_devtools\_api.js](http://code.google.com/p/page-speed/source/browse/chromium_extension/trunk/src/pagespeed_chromium/extension_files/fetch_devtools_api.js)

I have included the source here:

```auto

function fetchDevToolsAPI (callback) {
  // Attempt to load the extension API from each source file in order,
  // until one succeeds. On success, invoke the callback.
  var loadExtensionAPI = function (srcArray) {
    // ExtensionAPI.js expects WebInspector to be an object.
    window.WebInspector = { };

//HERE is the problem. IF condition is not satisfied, I guess. So it goes into the ELSE condition
which is the alert message shown in the screenshot.

    if (srcArray && srcArray.length > 0) {
      var script = document.createElement("script");
      script.async = false;

      script.onload = script.onerror = function () {
        // For Chrome 16 or newer, check if devtools is available.
        if ("devtools" in chrome.experimental) {
          delete window.WebInspector;
          callback();
          return;
        }

        // For Chrome 15 or ealier:
        // Once Extension API has been injected into the page,
        // WebInspector.injectedExtensionAPI() will be available.
        // Inject init_devtools_api to call the API initialization
        // function.

        if (WebInspector.injectedExtensionAPI) {
          // Fetch successfull... call init function and callback.
          WebInspector.injectedExtensionAPI(null, null, "pagespeed");
          delete window.WebInspector;
          callback();
        } else {
          // Fetch failed... try next URL.
          loadExtensionAPI(srcArray.slice(1));
        }
      };
      script.src = srcArray[0];
      document.head.appendChild(script);
    } else {
      alert("Whoops, it looks like the DevTools Extensions API is " +
            "unavailable from the remote browser.

" +
            "ExtensionsAPI.js must be be available under Chrome/" +
            "Application/<version>/Resources/Inspector/devTools.css, " +
            "which is currently only the case for local builds that " +
            "have 'debug_devtools': 1 set in GYP config. If you " +
            "want to play with it, copy the file from " +
            "http://trac.webkit.org/browser/trunk/Source/WebCore/" +
            "inspector/front-end/ExtensionAPI.js");
      delete window.WebInspector;
    }
  }

  // If the webInspector API is unavailable, then we need to fetch it.
  if (!window.webInspector) {

    // Try fetching from several different URLs:
    loadExtensionAPI([
      // A. DevTools.js includes ExtensionAPI plus a bunch of stuff we
      // don't need.
      document.referrer.replace(/devtools.html?.*$/, "DevTools.js"),

      // B. document.referrer should be the URL of the remote
      // devtools. For Chrome 16 or newer, devtools_extension_api.js should
      // reside at the same location.
      document.referrer.replace(/devtools.html?.*$/,
                                "devtools_extension_api.js"),

      // C. document.referrer should be the URL of the remote
      // devtools. ExtensionAPI.js should reside at the same
      // location for Chrome 15 or earlier.
      document.referrer.replace(/devtools.html?.*$/, "ExtensionAPI.js"),

      // D. Fall back on fetching the most recent version from trac.
      "http://trac.webkit.org/browser/trunk/Source/WebCore/inspector/" +
      "front-end/ExtensionAPI.js?format=txt",
    ]);
  } else {
    callback();
  }
}

```

Also where should I put the ExtensionsAPI.js, which it says to download from trac? Any ideas?  
Thanks.