The votes, which included those cast in all three of Sunday's elections, at the local, regional, and national levels, did not reach the electoral office in Falun in time.
As for why the bag failed to reach the electoral office, and who is responsible for the mix-up, the answer is not yet clear, with the Swedish postal service and Falu municipality each blaming the other for failing to adhere to their agreement.
The votes in question were placed before the official polling day of September 9th: in Sweden, some polling stations open in the weeks leading up to election day, allowing voters to cast their ballots in advance.
The papers should have arrived at the electoral office on Tuesday, but were not received until Wednesday, some hours after counting had begun. Under Swedish electoral law, votes cannot be counted if they are received after counting has started.
"We maintain that Postnord should have delivered," chairman of the electoral committee Jonas Åsenius told local newspaper Dalarnas Tidningar, adding that the postal service had an agreement with the Swedish Election Authority relating to delivery of early voting papers across all of Sweden's municipalities.
However, Postnord's Swedish head of production has denied that it was their responsibility to deliver the votes.
It's unclear what the next step will be, as it depends on whether the results are appealed. In which case the Election Review Board would look into the complaint.