ST PAUL: Fans decked out in purple shirts and scarves — and the occasional raspberry beret — turned out to groove to a revival of Prince's 1980s Minneapolis Sound at a tribute concert honoring the late megastar Thursday night.

Just before show time, a concert publicist announced that singer Christina Aguilera cancelled her scheduled appearance as she fights a "vocal illness." Singer Jessie J will replace Aguilera in the lineup for the sold-out concert at Xcel Energy Center in St. Paul.

"It is with a heavy heart that I cannot perform this evening and join the amazing talent onstage to pay tribute to the legend that was Prince. He will remain in our hearts and inspire our music until the end of time," Aguilera said in a statement.

A representative for Aguilera said she "has been advised by her doctors not to perform due to a vocal illness she has been trying to shake all week."

Pop star John Mayer bowed out of the concert earlier, citing a "change of schedule."

On the outdoor plaza before the concert, fans milled about and some danced. Sharie Tonsager, 46, who grew up in suburban Rosemount, looked forward to hearing the music of Prince — a star she never got to see perform in person.

"He was just original. He never cared what the media said. He just did what he did and loved what he did," said Tonsager, who was sporting purple-tinted hair.

Prince's younger sister, Tyka Nelson, described the concert featuring Stevie Wonder and Chaka Kahn as a public memorial to Prince, who died in April at his Paisley Park recording complex.

"I want them to get some closure," Nelson said of Prince's fans. "It takes time to kind of get over it, and I see that they are grief-stricken." She said there "definitely" will be future concerts.

Tori Kelly, Anita Baker and Doug E. Fresh also are included in the lineup. Prince's ex-wife, Mayte Garcia, has been added to the concert, and Prince will be represented by members of his inner circle, including Morris Day & The Time, Judith Hill and Liv Warfield.

The Prince family-sanctioned concert originally was planned for the Minnesota Vikings' new U.S. Bank Stadium in downtown Minneapolis, but was moved to the smaller Xcel Energy Center, home of the NHL's Minnesota Wild.

Prince's family initially announced the concert in late July, but details did not emerge until September. The wait frustrated Prince fans across the country who already had made travel plans without any guarantee of tickets. But organizer L. Londell McMillan, a longtime attorney for the late superstar, said it took time to put the details together because so many artists were involved.

McMillan told The Associated Press the change from U.S. Bank Stadium to Xcel Energy Center was a "business and creative decision." While the St. Paul arena seats 17,000 for the Prince tribute, compared with up to 55,000 for concerts at the stadium, its acoustics are considered good for a hockey arena.

Fans quickly snapped up tickets when they went on sale last month.

Prince died of an accidental painkiller overdose. The singer of hits including "Purple Rain," ''Let's Go Crazy" and "The Most Beautiful Girl in the World" was 57.