The Who have announced that the first four scheduled dates for their North American The Who Hits 50! tour will have to be postponed.

The decision comes as singer Roger Daltrey recovers from “an unspecified virus.”

The dates in question are California shows at the Valley View Casino Center in San Diego on September 14, at the Honda Center in Anaheim on September 16 and at the Staples Center in Los Angeles on September 21, along with the band’s date at the Colosseum at Caesars Palace in Las Vega, NV, on September 21.

The band’s slot at the iHeartRadio Music Festival in Las Vegas has been canceled. Further details about the rescheduling of the shows are to be announced soon. View the rest of the tour schedule below.

The Who Hits 50! Tour Dates

September 24 Portland, OR—Moda Center
September 27 Seattle, WA—KeyArena
September 29 Vancouver, BC—Pepsi Live at Rogers Arena
October 1 Calgary, AB—Scotiabank Saddledome
October 3 Edmonton, AB—Rexall Place
October 6 Saskatoon, SK—SaskTel Centre
October 8 Winnipeg, MB—MTS Centre
October 10 Minneapolis, MN—Target Center
October 13 Milwaukee, WI—BMO Harris Bradley Center
October 15 Chicago, IL—United Center
October 17 Detroit, MI—Joe Louis Arena
October 19 Toronto, ON—Air Canada Centre
October 23 Pittsburgh, PA—CONSOL Energy Center
October 25 Newark, NJ—Prudential Center
October 27 New York, NY—Madison Square Garden
October 29 Boston, MA—TD Garden
November 1 Washington, DC—Verizon Center
November 4 Philadelphia, PA—Wells Fargo Center
December 1 Toronto, ON—Air Canada Centre
December 4 Louisville, KY—KFC Yum! Center
December 6 St. Louis, MO—Scottrade Center
December 8 Kansas City, MO—Sprint Center
December 10 Denver, CO—Pepsi Center
December 13 Oakland, CA—Oracle Arena