Err 01 Communication between the camera and lens is faulty

ERR 01 is a lens to body communication error. Clean the lens and body contacts (put a small amount of alcohol on a Q-tip - do not use rubbing alcohol!!!). Try again. If that doesn't work, problem may be in lens or body. Using the flat of your fingernail, push in the contacts on the body inside the mirror box to clean any tarnishing between the contacts the the circuit (they are spring loaded). Try another lens - if the other lens works, then your problem is in the first lens. If it still gives the ERR 01 code then the problem is in the body.

Has the camera been impacted or had water/liquid spillage?

Err 01

Description: The communication between the camera and lens is faulty.
Resolution: Very gently clean the electrical contacts (highlighted in red) on the camera and the lens using a clean and dry cloth.

The contacts are the little gold coloured metal squares that touch between your lens and the body. Clean them with isopropyl alcohol (moistened glasses wipes work well) and see how you go.

Err 01

Description: The communication between the camera and lens is faulty.
Resolution: Very gently clean the electrical contacts (highlighted in red) on the camera and the lens using a clean and dry cloth.

Err 01: Lens to body communication error
1.The camera to lens communication is somehow being interfered with could be a problem within the lens itself, possibly the camera body, or something as simple as a smudged fingerprint on the lens mount contacts,
2. Check the lens and the contacts
3. Also check below link if you need a canon eos 5d service manual
http://goo.gl/1rXwuc

thanks

So, have you cleaned the contacts? Remove the lens and using a cotton swab lightly dampened with rubbing alcohol, clean the contacts on the lens and the camera body where they meet.

So, have you cleaned the contacts as you were advised? You do this by removing the lens and cleaning the contacts on the camera body and on the lens where they meet with a cotton swab lightly dampened with rubbing alcohol.

As a first step have you tried CAREFULLY (to avoid eraser bits getting inside the camera) rubbing the gold contacts on the camera and lens with a clean pencil eraser? That's one of Canon's recommendations. Good luck.

try to use another lens.
the problem is still,i think malfunction is on the body.
If solved,,,,,error is on the lens.
k.

This error means "Communication between the camera and lens is faulty. Clean the lens contacts." If you are using the same lens on both cameras, the problem is with the metal contacts on the rear of the lens where it communicates with the camera body. You can gently clean these contacts by using a clean pencil eraser. Make sure you hold the lens "bottom down" as you clean it so that the eraser debris falls to the table instead of inside the lens!