Thomas Camera Services Ltd - #Error01 on a Canon EOS 650D. This fault can be caused by either the body or the lens. For example: lens contact issues on the body or
CANON 24-70 2.8 L MARK 2 ERROR 01 REPAIR SERVICE DIAPHRAGM WITH 3 DAY TURNAROUND | eBay
ERR 01 - Canon EF 24-70mm f2.8 II Aperture Module replacement repair (full step by step) - YouTube