What does the error code "Err 99" on a Canon Rebel camera indicate and how can it be resolved?

The error code "Err 99" on a Canon Rebel camera indicates a general malfunction that could be caused by various issues such as lens communication problems or battery connection issues. To resolve this error, try cleaning the lens contacts, removing and reinserting the battery, or resetting the camera settings. If the error persists, it may require professional repair.