I have updated WordPress to latest version (4.0) this morning. After upgrading everything seems fine except qTranslate.
The editor does not show language switcher tabs and qtranslate throws following warning:
The qTranslate Editor has been disabled because it has not been tested with this version of WordPress. This step is a safety feature to provide the functionality of a secure WordPress. To reactivate click here (may cause data loss). To remove this message, please upgrade qTranslate to the appropriate version.
On activating plugin from the click here link above, language switcher tabs are visible but they do not work as expected. When text tab is clicked it show nothing.
I had resolved same issue in WordPress 3.9.2 with the help of this post but in new verson it doesn't seem to be working.