Error on upgrade from 1.3.4 to 1.4.0

I followed the "easy instructions" for 1.3.4 to 1.4.0 and I'm getting the following when I go to my website

Fatal error: Call to undefined method Language::getId() in /home/jdtcorp/public_html/catalog/model/cms/category.php on line 10

How can I fix this?

Did you get the new cms module from my site? Certainly I warned you that all modules would need to be updated. You need to redownload all the latest ones from my site.