I develop an addon for android mobile version of Firefox and use high-level api 'sdk/page-worker' for my processes. But when I updated Firefox to 38 version, sdk/page-worker don't work. I try to use source code from page https://developer.mozilla.org/en-US/Add-ons/SDK/High-Level_APIs/page-worker , but it don't work too. I mean that no errors, but background page not created. For example, if I using next source code: var pageWorker = require("sdk/page-worker"); var tmp = pageWorker.Page({ contentScript: 'console.log("Im loaded!!");' }); I haven't errors or warnings, and haven't log console "Im loaded!!". It's don't work only on android mobile version of FIrefox 38. On mobile Firefox 37 it work well (and desktop version of Firefox 38 work well to). It's a bug or a new feature? In changelog to Firefox 38 nothing about it... Thanks! I wait for your response!