Thousands of runners at a race in Leeds have been told finishing times will not be officially recognised because the 10km course was 23 metres too short.
More than 8,000 people took part in the Abbey Dash charity event on 27 October.
Age UK said the route, which was updated this year, "was re-assessed after the event", and the error found.
"We are extremely sorry that this has happened and apologise for any disappointment this may have caused participants," said organisers.
The race, which is in its 34th year, follows a route from Leeds city centre to Kirkstall Abbey and back. The route was slightly altered this year.
The 2019 event raised about £200,000, said Age UK.
Finishing times for the race would not now be recognised by UK Athletics, it added.
Stewart, one of the runners, said in a tweet he was "genuinely gutted" his time would not count as he had set a personal best time.
I'm genuinely gutted that the Leeds Abbey Dash times don't count this year as the course was incorrect and 23m short of 10k. I set a new PB that I'd worked really hard to get and its now been wiped from my record online. #abbeydash @TeamAgeUK— Stewart (@StewForsyth) November 26, 2019
The 2019 men's race was won by Omar Ahmed who clocked 28:38, while Charlotte Arter ran 31:34, which would have been the fourth best British women's 10km time, reported Athletics Weekly.
Lydia Curran, of Age UK, said the the route would be re-licensed for 2020.
"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," she added.
The Abbey Dash is not the first race to fall foul of measurement problems. Three years ago, the Greater Manchester Marathon race was found to be 380m short.
The Sheffield Half Marathon was cancelled amid confusion in 2014 after a lack of water for the runners.