More than 1,300 voters in the West Ashley section of Charleston County were mailed the wrong ballots, prompting local officials to resend correct ones.
The county elections office took blame for the error and has taken steps to send out the new ones covering federal, state and local races.
County Board of Elections and Voter Registration Director Joe Debney said the mistake came from within his office and hoped it would not cause anyone to lose trust in mail-in voting.
The problem affected two competitive races for seats on County Council.
Some voters in District 7 who requested early ballots by mail instead received printed ballots for District 6 when they should not have, while some voters in District 6 didn't receive an option at all, Debney said.
The error covers two precincts: St. Andrews District 28, covering the Shadowmoss area, and St. Andrews 3 and 4, which are closer to the U.S. Highway 17 area heading into downtown Charleston.
In the replacement ballots which went out Wednesday, voters are getting a message to discard their errant ones.
If they have sent them in already, their new ballot should be filled out and mailed in; it will replace the earlier one.
The replacement ballots, which feature a purple stripe on the envelope, should be delivered in three to five days, Debney said.
The District 6 race features Republican Darryl Ray Griffin, Democrat Kylon Jerome Middleton and Libertarian Melissa Couture.
District 7 features Republican incumbent Brantley Moody being challenged by Libertarian Sean Thornton.
The incorrect ballots were mailed to 1,324 voters.
The error also affected more than 200 voters who cast ballots early in person. According to the county, 225 people received the wrong ballot for Districts 6 and 7.
For them there is no remedy, the county said, as "state law does not allow for changes to those ballots and those votes will count," according to a media release.
The errors was discovered by a resident who detected an issue with their mail-in ballot.
Charleston County Democratic Party Chair Colleen Condon said she appreciated Debney's transparency in disclosing their office miscue. But she also warned the error could be potential grounds for a losing candidate to seek a new election. She was working to find a remedy so that any disenfranchised voter can be given a new chance.
County Republican Chair Maurice Washington sent out a note Wednesday warning Republican voters to check their ballots for accuracy.
Late in the day, Debney said another printing error was found on an undetermined number of ballots covering County Council District 4, where Democrat Henry Darby is running unopposed Nov. 3.