Updated

Nearly 50,000 voters in Franklin County -- Ohio's most populous county -- received incorrect absentee ballots in the mail, elections officials said Friday, revealing a major glitch that appeared to affect one in five ballots the county had sent so far.

Officials promised to have new ballots mailed within three days to the 49,669 voters who received the wrong ones.

"We want to make it clear that every voter who received an inaccurate ballot will receive a corrected ballot," the board said in a news release, according to the Columbus Dispatch. 

A list of voters who got the wrong ballot will be posted on the Franklin County Board of Elections website. 

Voters affected can wait for their new ballot or show up at the county board of elections during early voting hours to cast an in-person absentee ballot.

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Ohio Secretary of State Frank LaRose's office has directed the board to write a letter explaining the error along with the replacement ballots. 

“No vote will be counted twice. Every voter will receive an accurate ballot and that ballot will be counted," county Elections Director Ed Leonard said.

If a voter sends in both the replacement ballot and the original faulty ballot, only the replacement will be counted. If a voter only sends the original ballot, only their votes in races they were eligible to vote for will be counted. 

The chaos ensued after an unknown person changed the setting on a device that stuffs absentee ballots into envelopes. The mistake, which occurred Saturday afternoon, is thought to be an accident. 

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“While this process has taken longer than we’d like, we aren’t just determining a number. We’re determining and identifying each impacted voter," Leonard said during a press conference Thursday.

Ohio is one of a number of states that mails absentee ballot applications to all voters, but unlike other states, it has done so since 2012.

Franklin County already has sent 237,498 absentee ballots to voters who requested them in an election that is expected to have a record number of votes come through the mail. 

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Around 1.9 million Ohioans requested an absentee ballot in the state’s April primary, prompting an outcry when some were delayed in arriving. That forced some voters to cast their votes in person despite health concerns.

This is a developing story; check back for updates.