This problem can occur when you have installed the print service for the user acceptance environment and this is running on the same port. Because of this the print service for the production environment won't start and this gives the TS50001 error. 

This can be solved by stopping the SmartPrint UA service and setting this to a manual start. This way you can switch between the environments.

The other option is to to set the client to listen to another specific port. For this you need to

Run Edit SmartPrint Service Launch Options from the SmartPrint Start Menu folder and add the following argument:

--web-interface-port=[the port you want to use]

For example, to use port 9999:

--web-interface-port=9999

and click Edit service. After you restart the SmartPrint Windows Service, you will be able to access the web interface of the SmartPrint Windows Service at http://localhost:9999.

Error TS50001 can also trigger when the wrong user/password combination is entered.