Thousands of runners have been left frustrated after being told their charity 10k race times were not valid because the course was 23 metres too short.
The mix-up happened after organisers changed the course for the Leeds Abbey Dash on Sunday.
The race, which is in its 34th year, usually leads from the city centre to the ruins of Kirkstall Abbey and back.
But this year the start line was moved to the Headrow, where the Town Hall is located, and the loop around entertainment complex Cardigan Fields was removed to make the dash 'even faster'.
When officials measured the course once everyone had finished they found it was just short of 10K and sports governing body UK Athletics decided race times were invalid as a result.
Runner Eva McNamara, from Leeds, said: "It's really disappointing because I had run my best time. It seems to be a silly mistake to make.
"I feel a bit conned by this. I was already upset that I didn't get chocolate in my finishers' pack and now this."
Organisers said the race would be re-licensed for 2020 and this year’s participants would be eligible for a discount on the £26 entry price.
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On the Age UK website, the charity "apologised" for any disappointment, stating: "The race distance has been re-assessed after the event and due to slight alterations in the course landscape, the race distance was found to be short by 23 metres.
"This is approximately four seconds for athletes on a time of 29 minutes for 10k.
"We are extremely sorry this has happened and apologise for any disappointment this may have caused participants."
Lydia Curran, Head of Events at Age UK added: "The event is managed and organised with a trusted team which makes every effort to ensure that everyone has a safe and fun day.
"The route was re-licensed for 2020 and in the meantime we are so grateful for everyone who took part and raised vital funds to help improve the lives of older people in Leeds and the rest of the country."