This story originally appeared on Spotlight PA.

A design change Pennsylvania officials made to prevent voters from making a disqualifying error on their mail ballots appears to have backfired.

The issue — voters failing to write the final two digits of the year on the return envelope — is leading some counties to reject ballots in the primary, despite the state’s new advice to count them.

Last fall, the Pennsylvania Department of State announced it was redesigning the state’s mail ballot return envelope, in part to reduce the number of ballots rejected for lacking a proper date, which is required by law. This year’s envelope has “20” prefilled in the year line and leaves spaces for the voters to fill in the last two digits.

One election director said a “significant” number of voters who returned flawed ballots had not filled in the last two digits of the year, and other election officials around the state echoed that observation.

On the Friday before the election, Deputy Secretary for Elections Jonathan Marks sent an email to counties advising them to count ballots even if the envelope lacks the last two digits of the year.

“It is the Department’s view that, if the date written on the ballot can reasonably be interpreted to be ‘the day upon which [the voter] completed the declaration,’ the ballot should not be rejected as having an ‘incorrect’ date or being ‘undated,’” Marks wrote, citing a 2022 Pennsylvania Supreme Court case.

But the department’s emailed advice does not carry the force of law, and counties are making different decisions about whether to count the ballots. Votebeat and Spotlight PA contacted eight counties and found that Philadelphia, Allegheny, and Delaware counties are counting the ballots, while York, Lycoming, Lancaster, and Snyder counties are rejecting them. Montgomery County said it would make a decision next week.

It’s unclear exactly how many voters will be affected by rejections. Philadelphia said those figures would not be available until Thursday. In Snyder County, 10 of the 21 ballots rejected for dating issues were properly dated except for the last two digits of the year, Election Director Devin Rhoads said.

In Allegheny County, home to Pittsburgh, spokesperson Abigail Gardner said ballots with dating errors were the majority of the county’s mail ballots at risk of rejection, and this specific dating error was an “overwhelming” majority of those. Gardner said that until Friday, Allegheny County had been marking these ballots as improperly dated but changed that determination after receiving Marks’ email.

Lycoming County Election Director Forrest Lehman said his county will reject ballots that lack the final two digits. He added that such ballots make up a “significant” number of the ones his staff was rejecting, though he did not have exact figures.

Reacting to the Department of State’s advice, Lehman said, “I don’t know what they’re basing it on or why they decided to say it at the last minute.”