It was supposed to be the golden anniversary of the most famous rock concert in history, the event that crystallized in mud the free-love 1960s and the drawing power of a new generation of music stars.

But on Monday, Woodstock 50 appeared to be all but dead. According to a statement from the festival’s primary investor, the event — planned for Aug. 16 to 18 in Watkins Glen, N.Y., with acts including Jay-Z, the Killers and Dead and Company — was off.

“It’s a dream for agencies to work with iconic brands and to be associated with meaningful movements,” the investor, an arm of the Japanese advertising giant Dentsu, said. “But despite our tremendous investment of time, effort and commitment, we don’t believe the production of the festival can be executed as an event worthy of the Woodstock brand name while also ensuring the health and safety of the artists, partners and attendees.

“As a result and after careful consideration,” the statement continued, “Dentsu Aegis Network’s Amplifi Live, a partner of Woodstock 50, has decided to cancel the festival. As difficult as it is, we believe this is the most prudent decision for all parties involved.”