Manchester GreatCity Games organisers have apologised to Jessica Ennis for the mix-up that led to her being denied a personal best in the 100m hurdles.
Team GB heptathlete Ennis ran 12.75 seconds but her time was invalidated because nine hurdles, instead of the necessary 10, were put on the track.
"We're embarrassed and disappointed," said David Hart of organisers Nova.
"We're pleased Jessica has accepted our apology. We take full responsibility and it won't happen again."
Ennis beat reigning Olympic champion Dawn Harper and world silver medallist Danielle Carruthers in the race on a specially constructed track along Deansgate in central Manchester.
The 26-year-old's coach Tony Minichello told BBC Sport: "It's a mistake, it's unfortunate but we move on."