Tough Mudder 2021 has been cancelled less than 12 hours before it was due to go ahead.
Organisers and hundreds of athletes were geared up for the two-day endurance event at Dalkeith Country Park in Midlothian on Saturday.
But competitors received text messages just before 7pm on Friday night announcing the plug had been pulled.
The shocking news came after Midlothian Council revoked the event's license.
Participants were told they could apply for a refund or defer their tickets to 2022.
The hardcore race sees athletes cover ten miles of difficult obstacles.
Last year's Tough Mudder was scrapped due to Covid-19 restrictions, reports Edinburgh Live.
It's unclear if the pandemic has also affected this year's race.
It looked like this year's event would go ahead, but Tough Mudder bosses revealed the local authority had u-turned on their decision to grant the race a license just 48 hours after backing the decision.
They said they had been left “deeply frustrated” by the sudden cancellation in an email sent to competitors after apologising for the decision.
A statement from Tough Mudder released on Friday read: "At 18:27 this evening we received communication from Midlothian Council that our issued license to host this event was revoked.
"This intervention comes just 48 hours after the Council voted to support our event license, having reviewed the latest guidelines and considered the extensive safety measures we’d put in place.
"It’s a maelstrom of emotions right now: We’re grateful to the team for the months of work they put in with the Council, accommodating every request made and consistently demonstrating we could deliver a safe event.
"We’re deeply frustrated with this last-minute revocation.
"And we’re devastated not to be able to celebrate a return to in-person events with you, our Mudder community.
"We know you’re also devastated.
"Together we’ve waited over 600 long days to get back in the mud.
"And we’ve worked really hard to ensure our Scotland Mud Revival would be an unforgettable reunion.
"Over 75 crew members working around the clock to build the event.,7,000 finisher drinks on ice, 1,500 tonnes of dirt, 37 obstacles constructed.
"Instead of having a lot of dirty, tough fun with you all this weekend, we’ll be dismantling the fully constructed site.
"And longing for the day we get to give you, our Scotland Mudders, your long-awaited Tough Mudder experience."
They added: "We were ready to deliver your event.
"We know many of you have traveled hundreds of miles and spent good money to be here.
"The irony is not lost on us that just this past weekend, almost 16,000 rugby fans gathered together in Murrayfield, just 10 minutes up the road.
"We will continue our challenge of the decision to ensure other customers and other businesses do not suffer the same unreasonable last minute reversal of previously granted permissions."
A Midlothian Council spokesperson said: "Following receipt of a letter from Professor Jason Leitch there then followed a meeting with the Scottish Government, which provided clarification as to interpretation of the guidance.
"During the meeting it was made clear that a maximum of 500 participants per day are allowed at events in Level 2 areas.
"There was then a further meeting with elected members which resulted in the decision being taken to suspend the licence.
"Tough Mudder was informed of this decision.”
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