Error 99 When I turn camera on error 99 comes on screen,,,what does this mean Canon eos 350D

Error 99 is an "unspecified" error. It can sometimes be due to poor communication between the lens and camera. Here are some things to try:

1) Turn the camera off. Remove the memory card. Remove the lens. Replace the lens. Turn the camera on. Replace the memory card.

2) If that doesn't fix the problem, try cleaning the contacts on the lens and camera. Turn the camera off and remove the lens. Hold the lens upside down (contacts down) and gently rub the contacts with a clean pencil eraser. Be very careful to ensure that the eraser debris falls on the table and not into the lens. Repeat with the camera body, also holding it upside down (contacts down) as you clean. Replace the lens.

If neither of these work, then you need to send the camera in to Canon for repair.

1. Turn off the camera.
2. Remove the lens, battery, and CF card.
3. Allow the camera to sit without power for approximately 20 minutes.
4. Insert a fully charged battery, and turn on the camera.
5. Depress the shutter button as you would to take a picture.
Does the “ERR 99′ message appear? If it does, then the camera should be
serviced. If it does not, then please proceed to the next set of steps:
1. Turn off the camera.
2. Insert the CF card.
3. Turn on the camera.
4. Format the CF card in the camera.
5. Depress the shutter button as you would to take a picture.
Does the “ERR 99′ message appear? If so, then the CF card is the most
likely source of the issue. Try using a different card.
If the message does not appear, please complete the following steps:
1. Turn off the camera.
2. Clean the lens contacts by gently rubbing them with a pencil eraser
or soft cloth. Be careful that you do not let any debris fall into the
camera body.
3. Reattach your lens.
4. Turn on the camera.
5. Depress the shutter button as you would to take a picture.
If the “ERR 99′ message only appears when one particular lens is
attached, then that lens should be examined by a service technician.
If you see the “ERR 99′ with a different Canon lens attached, then the
camera should be serviced.