If a Client is not able to update/start after a upgrade of the server it has in most cases to do with the user not having administrator rights to install/update the program.
It can be Windows UAC( User Account Control ) that prevents consignor.exe to start Updateclient.exe
To solve the problem you can start the update manually by running the programfile called "UpdateClient.exe" the file is located in \Program Files\Consignor Client\
Remember to have administrator rights when running this file.
If it still not works, contact your administrator.