Ok, it seems that the UI is running on the same thread as the "server". I don't know hot btsync is built but this could lead to bad UI responses. I have following output on Chrome: Failed to load resource: the server responded with a status of 404 (Not Found) .../template.jswebui.js:2 startjquery-1.11.1.js:9592 Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check http://xhr.spec.whatwg.org/. webui.js:15 init languagewebui.js:51 checking browserwebui.js:73 checking user termswebui.js:99 initing store and global thanks for the support so far