Claim: in the 2016 California presidential primaries, people who had been registered for decades as Democrat showed up and found that their registrations had been changed to Republican. They could not vote for Bernie in the primary. So they were denied the vote. You cannot change your party affiliation within XX number of days of the election, and a person who is registered as a Republican cannot vote for any Democrat. I've seen many reports of people that had this happen to them. When they go to the county voting registration, the mail-in change of registration is shown to them and it has their signature on it. An exact, pixel-by-pixel match. A duplicate of the signature that was already on file in the system. It was purported that the voting registration system was hacked by Hillary Clinton during the primaries to prevent large voter turnout for her rival, Bernie Sanders. They picked young and progressive voters that would turn out in large numbers for Bernie, known supporters from Bernie's own (hacked) supporter database. Then they hacked those particular people, leaving alone the people who supported Hillary. Thus, they swung votes away from Bernie and toward Hillary. If it can be done once, it can be done again. Voting systems are beyond insecure.