Err 99
Description
This is a general error that can occur because of several different reasons.
Resolution
- Very gently clean the electrical contacts (highlighted in red) on the camera and the lens using a clean and dry cloth

CAUTION:
When cleaning the contacts take the following precautions:
- Do not wipe the contacts with a wet cloth
- Do not touch the contacts directly with your hands. Touching them with your hands could cause corrosion, which would cause the camera to become inoperable
- When cleaning the contacts on the lens side, be careful not to damage the lens surface
If the error message is still showing, then it is necessary for the camera to be inspected by a Canon Factory Service Center.
Please follow this link to begin the repair process:
https://www.usa.canon.com/support/service-and-repair