Are you certain there is no remote desktop installed at all on the machine where you are using Quick Support? If there is, Quick Support may launch the previously installed version. You'll be able to see Quick Support when it launches to verify.
David, thanks for the quick reply. I had installed RemoteDesktop as a test, but exactly the same version (download from yesterday), at the time of starting QuickSupport the application was then uninstalled.
Error Message: The Files can't be sent to <...>: it is required to upgrade Remote Desktop on computer <...> to a newer version.
QuickSupport Version: 2.4.0.48_net4.5.1
RemoteDesktop Version: 2.4.1.19_net4.5.1
Both downloaded yesterday.
I get exactly the same error message as Jens W with file transfer from Remote Desktop console 2.4.0.48_net4.5.1 to client computer using Quick support 2.4.1.19_net4.5.1. Error message telling me that QuickSupport.exe on client computer is outdated.