P.S. When I change lens to my Canon EF 28-135mm 1:3.5-5.6 IS, I don't get the Err 01 message - no problems at all, which suggests the problem is my Canon EF 100-400mm 1:4.5-5.6 L IS lens.
Hi JAYSTATON. I'm having similar problem. I purchased a Canon EOS R6 just over a year ago & initially didn't have any problems with my EF 100-400mm 1:4.5-5.6 L IS lens using my Canon EF-EOS R Mount Adapter. Then, a few months ago, I started gettin...
