Tweet Button #undefined


I’ve got problems with the tweet button on my page. The button label displays “Tweet #undefined” and does not allow counting tweets. The data_count url is set to undefined and it is not possible to use the button properties. I only got these problems when I try to use the “Share a link” button (guess the other buttons are working fine).
Creating a new button and adding it to my page leads to the same results but strangely the same code works on other pages. I googled for a solution and it seems that I am not the only one having this problem:

How can I solve this problem?


I’ve reported this issue to engineering. You can follow along here:



To help me collect data about this problem – are you using the Tweet Button directly or are you using a third party intermediary like the AddThis toolbar?


I’m having the same problem on a client’s PC in IE8 & IE9 (firefox works fine) on SpeedTV article pages like:
where it displays fine for a minute, then each menu tab & link button turns into a Tweet button displaying ‘Tweek #undefined’. And you end up with dozens of these tweek buttons & a very slow responding page.


Thanks for your reply.
I’m using the Tweet Button directly.


Hey everyone. Just deployed the fix for this. Please let us know if you run into any further issues.

A quick explanation of what happened here:

Because we continue provide browser support all the way back to IE6, we use a lot of wrappers to fill in pieces of JavaScript functionality (in this case, the quite rudimentary Array.indexOf function that was only introduced to IE in version 9.) The polyfills we write are completely self contained, and not exposed to your pages, but in this case another framework elsewhere in the page bled into our code, resulting in this wildly unexpected behaviour.

We recently updated widgets.js to make use of more modern browser’s native methods (since they’re faster.) The issue here was that another piece of code in the page added the prototype Array.indexOf—which we mistook for the native method—but not in a way that was fully compatible with the native behaviour (it returned undefined rather than -1 when failing to match an item in the array.) This caused some false positive matching in various pieces of our code, which in turn caused the bugs you see above. We’re confident this was a very fringe bug, due to it requiring a specific other modified prototype to be in the same page, but obviously it still sucks, and I’m sorry for that, and we’ll be more strongly validating the returns of wrapped, native functions when optimising our script in the future.




thanks. The Tweet Button looks good again on my page and I found no further issues.


This issue should now be resolved. Thanks!




jaime les belle femmme




Will the benward prescription work in this case…

We’re having a problem sharing via twitter when we remove our original block of OG tags and replace with Yoast only (Yoast is the Wordpress SEO plugin). Our issue is related to this:

We’re seeing this problem on pages such as (but that page is live with our original block of code so you won’t see the problem).




Mike: please open a new support thread with more information about your specific issue. It’s unlikely a bug patched two years ago still applies.