How are you trying to connect to Spotify? With a web browser on a PC, with a dedicated app on an Android device, or with something else?
If you paste the error message into Google you'll be taken to loads of links (most/all of which seem to refer to the Android app). You might well find a solution there.
One post suggests that the problem can be cured by deleting all data from the app and starting again - but that seems a bit drastic because you'll then need to download all of your music again.
Assuming that your problem does, indeed, relate to an Android device, it might be best to try a forced reboot of your phone first (which is probably achieved by holding the power button down for 10 seconds but that might vary between manufacturers). That solved a problem with a malfunctioning app for me earlier today.