Already with early voting, there are reports of voting machines flipping votes:

In every recent election, there have been reports of voters pressing one candidate’s name on a touch-screen machine, only to have the opponent’s name light up instead.

It can be unnerving for voters and often leads to allegations that the machines have been “rigged” to favor one candidate over another.

Enter election 2016, when the word “rigged” is more politically charged than ever. In the first few days of early voting, there are already scattered reports of vote-flipping machines in North Carolina, Texas and Nevada.

Machines flipping votes are usually due to user error or to the machine malfunctioning:

The North Carolina chapter of the NAACP sent a letter to the state’s board of elections Monday after voters complained that machines had flipped votes in five counties. The group noted that, in each case, the voter was able to correct the error before the ballot was cast. But it asked the board to remove malfunctioning machines and to post signs reminding voters to check their ballots before submitting them.

The board replied that it takes the concerns seriously and advised voters to double-check their ballots. It said the machines were tested before the election and are recalibrated each day before voting begins. And, if needed, problem machines would be taken out of service.

In Texas, a handful of voters in at least three counties reported that they had selected straight Republican tickets, only to have Clinton/Kaine pop up instead of Trump/Pence. Local election officials blamed user error and said there was nothing wrong with the machines. There were similar reports in Clark County, Nev.

[T]he real problem is that voting machines used in much of the country are old, more than 10 years in most places. The machines rely on outdated technology — some of it is from the 1990s — to calibrate the touch screens. And the hardware is starting to wear out.

As voters increasingly rely on technology to register to vote and cast their ballots, it is vital that election officials ensure that: (1) the technology is functioning properly; (2) the technology does not have any software or hardware vulnerabilities; (3) the technology is frequently tested; (4) functional low-tech backups exist; (5) election officials and poll workers are well-trained on the equipment and able to help voters; and (6) any complaints of malfunctions are taken seriously to ensure both voter confidence and actual accuracy.