Party at the Palace and Party at the Park have been cancelled amid ongoing uncertainty surrounding coronavirus restrictions.
Organisers said they were left with “absolutely no alternative” but to cancel the two three-day festivals due to be held in Linlithgow and Perth.
Acts such as the Manic Street Preachers, Kaiser Chiefs, Sophie Ellis Bextor and The Snuts were due to play at the festivals, scheduled to take place in August.
Both events were expected to pull crowds of up to 18,000 people each, as well as employing around 1000 artists, staff and crew members.
In a statement, organisers said: “We feel particularly let down by a lack of communication and guidance from Scottish Government. There seemed to be no understanding that our events take months to plan.
“Relying on three weekly updates, conflicting advice and unclear guidance made it impossible to give assurances to our customers, artists, staff and traders.”
Scotland is due to move to level zero restrictions on July 19, which would see outdoor seated and open space events allowed to operate with a maximum of 2000 people, with outdoor grouped standing events capped at 1000 people.
The First Minister has indicated that all major coronavirus restrictions could be lifted on August 9.
Ticket holders have been advised to visit the Party at the Palace and Party at the Park websites for more information.
A Scottish Government spokesperson said: “We understand the impact the pandemic is having on the events industry and we are doing all we can to allow events to take place while continuing to ensure appropriate safeguards are in place. Restrictions that are required to protect public health will not stay in place for a moment longer than absolutely necessary.
“We want event organisers to be able to plan future activity with confidence, but we must continue to move very carefully to ensure continued suppression of Covid-19. We know that music festivals and local authorities need guidance on what will be required when we move beyond level zero and we are working to make sure that guidance is available as soon as possible.
“The First Minister’s statement on July 13 confirmed that the size of events and stadia attendances will increase outdoors to 2000 seated and 1000 standing, and indoors to 400, whilst organisers can also apply to stage larger events.
“The next review of restrictions will be in the week before 9 August when we hope to be able to move beyond level zero.
“Operation of the insurance market is reserved to the UK Government. The Scottish Government has been pressing the UK Government to take action in this area for a considerable period of time to help event organisers proceed with confidence when planning events.”