Hi Stephen. Welcome to justanswer.
Does this error comes with all the lenses?
Turn on the camera and while it is on, just Open the flash card door and when the door slides just push it back. This will reset the camera. Check if the error goes away or not.
Then the problem is with this lens.
ERR99 is a general error, but often the cause of the error is lens communication. This could be for many different reasons. For example, if the aperture assembly on your lens is broken and needs to be replaced, the camera will tell your lens to change the aperture, the lens can’t because the aperture assembly is not functioning, and so the camera will not have any confirmation that the lens obeyed it’s command. The result? Error 99.
Try the lens on a different camera, or try using a different lens on your Canon camera. This way you will know if the lens is causing the problem. If the lens is the problem, you will need to send the lens to the lens manufacturer for repair.
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