Similar to the case https://bugs.webkit.org/show_bug.cgi?id=66205, but using HTTPS GET and POST calls, I have an Error: NETWORK_ERR: XMLHttpRequest Exception 101. It takes place also under Linux (Ubuntu 14.04.2). No problem with HTTP. (Currently, I solved the problem by using asynchronous calls on the server side.)
Qt is no longer supported in WebKit trunk, so closing as INVALID. Please see <https://lists.webkit.org/pipermail/webkit-qt/2013-October/003878.html>.