If you get an error while trying to log in, fix the problem by either;
1. checking your internet connection. If your phone's connection is weak, the login process might not succeed. In this case, try again until it works. **This is the common solution.
2. checking if you password has not expired. Test your password by loggin in here: https://enter.cput.ac.za/cas/login If you DO NOT get an error, then try 1 above. If you get an error, then reset your password here: http://www.cput.ac.za/students/about/it/password