The widespread voting problems in last month’s general election in Northampton County were caused by the vendor’s lack of quality control and human error.

These are the conclusions announced Thursday after an internal investigation to try to pinpoint why Election Day votes did not register electronically for some candidates and why the machines’ screens did not display information properly.

Most of the problems occurred when voters were casting ballots for judicial and school board candidates who had cross-filed (their names appeared on both the Republican and Democrat ballots) and in the district attorney’s race.

Fortunately, the backup paper ballot system that was incorporated into the 320 new voting machines purchased for $2.8 million from Election Systems & Software of Omaha, Nebraska, led to an accurate count, according to County Executive Lamont McClure and Adam Carbullido, ES&S senior vice president for product development.

The problems were caused by the misalignment of instructional texts on the ballots for the judicial and school board races, which caused votes to be credited to different lines, they said.

In addition, Carbullido said, as many as 30% of the machines had been incorrectly formatted, leading to inconsistent screen performance.

He said the company takes full responsibility for the errors.

“This was an unfortunate human error, and we are glad to have it resolved,” McClure said. “Moving forward, Northampton County is committed to demanding accountability from ES&S.”

No decision has been made on whether to demand a partial refund from the company.

The county bought the machines to comply with a new state law that requires a paper trail of votes cast.

Also Thursday, Gov. Tom Wolf’s administration asked a federal court to reject a challenge to its certification of voting machines bought by Philadelphia and Northampton.

In a federal court filing, Wolf’s administration said the plaintiffs, former Green Party presidential candidate Jill Stein and several supporters, knew Pennsylvania was about to certify the ExpressVote XL touch screen system when the sides settled the election-security lawsuit.

“Many months had passed” before the plaintiffs objected to the certification of the machines, made by Omaha, Nebraska-based Election Systems & Software, lawyers for the Wolf administration said in the filing.

The settlement agreement’s terms are clear and the ExpressVote XL complies with them, they wrote.

The court fight casts doubt onto how 17% of Pennsylvania’s registered voters will cast ballots in the April 28 primary election, as well as next November, when the state is expected to be one of the nation’s premier presidential battlegrounds.

The plaintiffs say certifying the ExpressVote XL violates the settlement agreement, in part because the machine does not meet the agreement’s requirements “that every Pennsylvania voter in 2020 uses a voter-verifiable paper ballot.”

The Associated Press contributed to this story.