What error in the election of 1800 provided proof the original system of the presidential electors to be flawed

The error in the election of 1800 provided proof the original system of the presidential electors to be flawed is that All electors voted for both Thomas Jefferson and Aaron Burr. In this election, Jefferson won the presidential election with 73 votes to Adams's 65.

The error of the election of 1800 that provided proof that the presidential electors system was flawed is that All electors voted for both Thomas Jefferson and Aaron Burr. Both candidates received 73 votes and this exposed the flaws inherent in the original system.