This ad is for the repair of your Canon EF 24-70mm 2.8 L lens.  If your lens is causing the "Err 01" message on your camera, I can repair it.  This problem is caused by a faulty aperture mechanism circuit ribbon.  I have the parts in stock and can turn the repair of your lens around in a couple of days.  If you have any questions please contact me.  At your service, Steve.