A customer reported us that he can't use one specific part of a web application we provide. We could not reproduce it and for us and other thousands of customers there was no problem. So we decided to have a desktop sharing meeting. In response of my questions he said that this problem encountered two weeks ago and that he has problems with other websites too.

I saw that there is a syntax error in the jQuery library. We introduced a new feature two weeks ago where we decided to use jQuery in noConflict mode parallel to prototypeJs. That solves the question why only this part does not work. I updated jQuery to 1.5.1 but the error was still there.

When I opened the source code I could not believe what I saw. The code was completely unfamiliar. Every extern css and js files were put inline with some changes. I deactivated all extensions for Firefox and the code is still messed. The customer uses a UMTS stick which made me suspicious. I googled for "umts comprission stick" and parallely I opened the page in IE. To my surprise in IE there were no problems, which made my suspicion about compression by the UMTS provider unsteady. But I was curious and read some results in Google. Et voilà, the used UMTS client does this compression and it's only for some browsers (i.e. not for IE and Opera). 

There was no option to deactivate this and I installed the Firefox addon "Modify headers" to send Cache-Control no-cache on every request, it's not good but works for now.

The error was: "missing } after property list" (see attachment).

Client: web'n'walk by T-Mobile

See also (in German):  http://www.joomla-office.net/cms/datenkomprimierung-bei-umts.html