The project I'm working on uses a window.onerror event handler to report user problems. I've noticed a single user that just cannot seem to load the Google Analytics script. Our site doesn't see a lot of traffic so I'm not sure how widespread this is, but so far it seems to just effect one user.

His user agent is: "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.17) Gecko/20080829 Firefox/2.0.0.17".
The error message Firefox gives is: "Error loading script".

Additional note: The site references several other javascript files. However, the analytics reference is the only one to an external domain and the only script reference at the bottom of the page, just before the closing body tag.

Has anybody else run across this, or have any idea what could be the issue? Thanks!

The project I'm working on uses a window.onerror event handler to report user problems. I've noticed a single user that just cannot seem to load the Google Analytics script. Our site doesn't see a lot of traffic so I'm not sure how widespread this is, but so far it seems to just effect one user.

His user agent is: "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.17) Gecko/20080829 Firefox/2.0.0.17".
The error message Firefox gives is: "Error loading script".

Additional note: The site references several other javascript files. However, the analytics reference is the only one to an external domain and the only script reference at the bottom of the page, just before the closing body tag.

Has anybody else run across this, or have any idea what could be the issue? Thanks!

• javascript
• firefox
• google-analytics

5 Answers 5

This problem occurs when leaving a page in Firefox before all scripts have finished loading. So I assume that it is safe to ignore the error.

You don't see this error in the Firefox error console, but you can make it visible by binding an alert to the window.onerror event. Then you will be able to see the alert box for a small amount of time and get the following error in the error console:

[11:35:57.428] uncaught exception: [Exception... "prompt aborted by user"  nsresult: "0x80040111 (NS_ERROR_NOT_AVAILABLE)"  location: "JS frame :: resource:///components/nsPrompter.js :: openTabPrompt :: line 462"  data: no]

I'm using the following check to ignore this error in my onerror handler:

if (navigator.userAgent.search('Firefox') != -1 && message === 'Error loading script') {
    // Firefox generates this error when leaving a page before all scripts have finished loading
    return;
}

This is a rather random guess, but I wonder if the user is using an add-on like NoScript to control script execution and is not allowing scripts from Google Analytics to run. I know this is possible because it's what I do :) I don't know if that would show up as the error you're seeing.

I have a site with over 80 pages, all that employ JavaScript error trapping. My site serves well over 2000 pages a day and I get about ten "Error loading script" scripting errors each day from Firefox browsers. It is beginning to really annoy me and I am becoming convinced that it is a problem in Firefox.

I can discount the NOSCRIPT suggestion because the script loads in the head of my pages where there are no NOSCRIPT tags.

I can discount the 'external domain' suggestion because I have two sites that suffer this problem and in both cases the JS library files are located on the sites own server.

I have carefully checked every library file and web page using JavaScript Lint and I have discovered scripting errors and questionable scripting techniques. All these problems have been corrected but this has not provided any sort of cure to the "Error loading script" problem.

My pages do load several JavaScript library files that do not have this problem and the only difference is the size of the files. Most of the files are under 5KB but the problem file is 17KB.

Could the size of the library file be the problem?

Aagh!

We had the same issue and after examining our CDN logs, we discovered that Firefox triggers the onerror event when a script returns with HTTP status "304 Not Modified", so a cache hit. In fact, Firefox (tested with Firefox 12 at time of this writing), seems to trigger onerror event for all HTTP statuses except '200 Ok'. Other browsers behaved differently in our experiment: Chrome (19) triggered onerror only on '407 Proxy Authentication Required' and Opera (12) on 100, 101, 204, 4xx and 5xx.

I'm sure this is long resolved.. but to anyone who stumbles across this page: this error is triggered by firefox when an external script fails to load (it's easy to find the code that triggers this in the source code). We were catching these errors on our site and it turned out that we were returning 404s for the script, so I suggest looking at your logs as one possibly source of this error.