"My sincerest apologies to all of my fans," the singer said in a statement released Saturday. "My intention was to complete the rest of the tour, but tonight at sound check in Anaheim I realized this wasn’t possible."
The singer, 23, added that she'd been resting her voice "for days," but it didn't help: "When I tried to sing, nothing came out.”
Shows were canceled in Anaheim, Universal City, Santa Barbara, and San Jose, Calif., as well as Spokane and Everett, Wash. Refunds will be available on Monday.