Delays in easing Covid restrictions in Scotland have been blamed for the scrapping of Out East at Gosford House - which was used for the filming of Outlander and Princess Switch movies.
Organisers say they had reached a "turning point" in having to spend money on infrastructure and fees for acts without knowing if restrictions would be eased in time.
Audiences numbers at outdoor events are currently capped at just 2000 at Level 0 under Scotland’s route map out of lockdown. East Lothian is currently at Level 1.
Mainland Scotland is not expected to reach Level 0 until 19 July at the earliest – three weeks later than envisaged and less than three weeks before the event was due to be held.
The event – billed as “a new family friendly festival for the carefree, the intrepid and the brave” when it was announced – had been due to go ahead with social distancing measures in place.
It is understood that problems had also arisen behind the scenes over the proposed site of the festival, which Sister Sledge, Ministry of Sound Classical, Glasvegas, The Futureheads and Callum Beattie were all due to appear at.
Organisers have admitted they are now planning for the event to happen next year, but at another location, in the grounds of Dalkeith House in Midothian. Both Sister Sledge and Ministry of Sound Classical have been confirmed as headliners.
An official announcement said: “It is with great sadness that we must announce Out East will no longer be taking place at Gosford House this August and will be postponed until 2022.
“We have been closely monitoring the current situation and the announcement that level 0 is being pushed back by three weeks means we simply cannot move forward with our plans.
“The health and safety of everyone involved with and attending the festival is paramount, and we are at a turning point where equipment costs, infrastructure and artist deposits etc become unrecoverable unless we act now.
“With this in mind, it is just not possible for the festival to go ahead as planned.
“We have been doing everything within our power, but for an independent event such as Out East, this means a huge gamble if we were to venture further forward.”
Although many of Scotland's summer festivals have fallen victim to the country’s ongoing curbs on live events, Out East was one of several festivals due to go ahead. Others include the annual Fringe by the Sea festival, which is due to be staged across North Berwick in August.
The Out East statement added: “Sadly we have had to look for a new festival home next year. We cannot thank Gosford House for all their support in trying to make Out East 2021 happen.
"The festival will be moving to the beautiful Dalkeith House on 6th & 7th August 2022.
“Further information for ticket-holders will come from our ticketing partner, Skiddle, as will more information on a bespoke transport service from East Lothian to and from Dalkeith and some nice little bonuses for carrying your ticket over to 2022.”