This error may have 2 possible causes:
1. You have selected as server a computer, on which the Projetex Server is not installed.
After Projetex Workstation has been started, please click the Server button and check whether the correct IP-address is entered. If Projetex Workstation and Projetex Server are installed on the same computer, choose the "This PC" option. Then try to connect to the Projetex Server.
2. Projetex has been updated partially on your computer (i.e. only the Projetex Workstation has been updated).
Update your copy of Projetex. For this, download the latest build of the program from your account at https://clients.translation3000.com and install both the Projetex Server and the Projetex Workstation over the current copy of the program without uninstalling it.