When installed, the port number used to access the server part of the Offline application is set to: 50123. An error dialog may display this error, to report this particular error.
If the port is occupied, another port may be used instead. The port number is defined in the file: C:\ProgramData\Signifikant\Assert AnyTime\WWWRoot\App_Data\anytime.setup.config. Add or change an element <IISExpressPort>55123</IISExpressPort> to defined a new port number.