Read the below from central Career Services:

Having trouble logging into Handshake or is your Handshake account pending? 

A Handshake account has already been created for every enrolled student with their @UMAIL.UCSB.EDU address. Information from the Registrars such as major, GPA, class level, etc. is already in Handshake. You simply need log in via “single sign-on” at https://ucsb.joinhandshake.com with your NET ID and your password. Your NET ID is everything before your @ucsb.edu so you don’t have to enter a full email address, just the NET ID. We will not accept separate account registrations so please don’t attempt to create an account or to sign in with your @ucsb.edu address because the system will not recognize you.

For more information, please review this page: http://career.sa.ucsb.edu/students/handshake

Do your qualifications not match what the job description is asking for?

Employers can indicate specific qualifications based on major, class level, GPA, work study eligibility, etc. As you view each position in Handshake, you will see how closely your qualifications match their qualifications. Regardless of how closely you match, YOU CAN APPLY TO ANY JOB! So, apply and don’t let this discourage you.

Is your major, class level or graduation date incorrect in Handshake?

Information such as these are fed into Handshake three times a week from the Registrar’s Office. You can change this in Handshake, however, it will likely change back. From your profile, click on the edit button beside your class level to adjust that or click on the edit button in the Education section to adjust major and graduation date. This can be a quick solution but you will have to visit the Registrar’s Office to investigate further why your information may be incorrect.