ReferenceError: Drupal is not defined I am working on a production site, moving settings from a development site for a mobile environment. However, I am receiving the above error. I can not figure out what is causing this error. It does not matter what theme I change my jquery mobile environment too. I've checked all the modules and they seem to be the same versions. The only thing I can see that is different is in the development site I can uncheck/check the block cache, on the production environment I can not do this.
Sounds like an issue with the ordering of the javascript files. Drupal is defined in 

/misc/Drupal.js

var Drupal = Drupal || { 'settings': {}, 'behaviors': {}, 'locale': {} };


Check Drupal.js is added to your HTML source, prior to when that variable is requested.