Security error when accessing the stylesheets

This article by Carsten Emde describes a problem that may arise when the RTE tries to access the stylesheets.


In Firefox, the following error message is written to the JavaScript console:

“[A security error occurred. Make sure all stylesheets are accessed from the same domain/subdomain and using the same protocol as the current script.”


In order to prevent the error, everything of a web page needs to be in the same domain, in the same subdomain and, more importantly, be transmitted with the same protocol. This is not a special feature of Firefox; IE8, Safari, Chrome, Opera and friends are behaving similarly.

Initially, a user is connecting to our Web site “”, and the content of the Web site including CSS files is loaded. In order to use the calendar and trouble ticket extensions, the user needs to login. As required for this purpose, the login page is accessed via https and some content is then transmitted using this protocol. Any further attempt to run RTE in this situation, irrespective of whether subsequent content is transmitted via http or https, crashes with the security error. This is the result of the browser storing the transmission protocol and the domain of the content, so it can refuse to load dynamic pages, if they do not match the available content, or if there is no coherent origin and protocol of the content.


I therefore changed the baseURL of the page to “” to force a coherent protocol throughout an entire session - even when it is not needed. Unfortunately, it still did not work, because I simply forgot to flush the browser cache. Of course, I flushed the server caches (as always), but in this special case, it is important that the browser cache be flushed as well to remove any non-https content at the client site. Only if the entire content of a Web page has been transmitted using the same protocol, it is considered safe. After I flushed the browser cache, RTE popped up and started to work as I was used to it from the backend experience.