Suffering from a "long-term illness," the 41-year-old will not be able to return to work "until further notice," said the Bayreuth Festival's spokesman, without giving further information about the nature of Katharina Wagner's illness or when she might return.

The festival's 2020 edition, scheduled to begin on July 25, had already been cancelled due to the coronavirus pandemic. But had it gone on as planned, Katharina Wagner would have not been there to supervise the beginning of rehearsals in April, said Georg von Waldenfels. "It is serious," added the chairman of the Friends of Bayreuth Foundation. "But at this point, she has not been tested positive with COVID-19."

No good beginning to the year 2020

Since 2008, the great-granddaughter of Richard Wagner (1813-1883) has been the artistic director of the festival he founded – initially with her half-sister Eva Wagner-Pasquier as co-director, and since 2015 bearing sole responsibility.

Read more: 11 things to know about Wagner and Bayreuth

In 2013 Hans-Dieter Sense joined the festival as its managing director, succeeded in 2016 by Holger von Berg. In Katharina Wagner's absence, Sense, 81, is now returning to act as interim director in tandem with von Berg.

"I am shocked," said Nicolaus Richter of the Richard-Wagner Foundation in Bayreuth at the news of the illness. Not quite six months ago, Katharina Wagner had extended her contract until 2025.

2020 has already been a fateful year for Wagner. In December 2019 her associate Peter Emmerich, the Bayreuth Festival's long-serving press spokesman, died unexpectedly. Her planned stage production of Richard Wagner's opera "Lohengrin" in Barcelona was called off due to the coronavirus pandemic. Then came the cancellation, at the end of March, of the 2020 Wagner festival in Bayreuth.

Not a normal family enterprise

Established in 1876, the Bayreuth Festival has always been headed by a member of the Wagner family: first by Richard Wagner himself, then by his widow Cosima, his son Siegfried, and after his death in 1930, by Siegfried's widow Winifred Wagner. Reopened after World War II, the festival was managed by the third generation: Richard's grandsons Wieland and Wolfgang – first in joint directorship, then after Wieland's death in 1966, by Wolfgang Wagneralone.

The era of Wolfgang and Wieland Wagner was known as "New Bayreuth," a time of freeing the festival from its entanglement with Nazi ideology. Not quite half a century later, Wolfgang Wagner's daughters Eva and Katharina began their tenure with a renewed revamping of the festival's image and a departure from traditions. In this, Katharina was the most energetic party and the festival's new face.

Read more: 9 myths about Wagner and Bayreuth

On the artistic side, her highly derivative staging of "The Mastersingers of Nuremberg" in 2007 turned the operatic comedy's story upside down. While traditionalists were up in arms, Katharina Wagner established her credentials as a courageous and even daring stage director.

A new business structure for Bayreuth 

The fourth generation of Wagners opened up the Bayreuth Festival and dispensed with many of its dusty and unquestioned rituals. No longer the exclusive domain of Wagnerians sometimes spending years on waiting lists for a ticket, premiere performances were now broadcast live on television, relayed to public places or movie theaters and streamed on the internet. These innovations moved Bayreuth in the direction of its founder's utopian vision: Richard Wagner had called for a festival that would be free and accessible to all.

There was also a new business model, with the limited liability company once solely owned by Wolfgang Wagner now split among four parties, making business decisions far more complicated.

A fresh wind in Bayreuth

Katharina Wagner's tenure has coincided with the costly but overdue, years-long refurbishment of the Festspielhaus, the Bayreuth Festival Theater. Establishing "Taff," a new consortium of sponsors, Katharina Wagner reduced the weight of the association Society of Friends of Bayreuth in the festival's inner workings. The association has shares in Bayreuth Festival Limited, along with the national, state and local governments.

Another innovation came in 2017: "Diskurs Bayreuth" (Discourse Bayreuth), with podiums addressing the festival's mixed and controversial history, modern performances and premieres . The enterprise is flanked by masterclasses for young soloists led by established veterans of the Bayreuth stage.

Read more : 8 similarities between Wagner and Rammstein

Wagner takes greatest pride, however, in having introduced operas specially staged for children aged 6-12 as a side-act to the main festival. "They're very popular," she explained to DW in 2013, "and we try to stage them at the highest artistic level." In the past decade, the main stage has seen an uptick in the quality of Wagnerian singing as well.

Productions panned and lauded

Katharina Wagner's 12 years at the helm have seen plenty of controversy with multiple productions panned, musicians protesting insufficient rehearsal time and sponsors, directors and conductors turning their backs on the festival. Not only older Wagnerians have observed that Katharina Wagner has dispensed with many a Bayreuth tradition for no apparent reason other than that it was a tradition.

But beginning 2017, the festival director has seen an unbroken chain of successes: "Mastersingers"  (2017) as staged by Barrie Kosky,"Lohengrin" (2018) interpreted by stage director Yuval Sharon against the backdrop of powerful imagery devised by the famous German artist Neo Rauch – and the frenetically celebrated production of "Tannhäuser" (2019) by director Tobias Kratzer. A critic wrote: "Bayreuth is no longer what it once was. It's better."

"We have to just wait and hope that Katharina is back on board again soon," said Georg Freiherr von Waldenfels on Tuesday to the German press agency dpa. The Bayreuth Festival can in fact hardly be imagined should Katharina Wagner's absence be enduring.