topic Re: EOS 90D Error 01 in EOS DSLR & Mirrorless Cameras

EOS 90D Error 01

ken002 — Mon, 30 Jun 2025 13:47:39 GMT

I was shooting a wedding and half way through it I started receiving this error. I switched lenses and it continued, so I had to use my older camera. Please help!! What do I need to do?

Re: EOS 90D Error 01

deebatman316 — Mon, 30 Jun 2025 15:41:12 GMT

What lenses are you using please provide the FULL NAME of ALL lenses being used. Saying “EF-S 18-55mm” IS NOT a complete name. Canon has made 9 different versions of that lens with the same focal length. I have example lenses below to help you identify your lens model below. Also are you using any accessories attached to your camera. If so what are they.

Re: EOS 90D Error 01

ken002 — Mon, 30 Jun 2025 15:58:39 GMT

No accessories used.

Re: EOS 90D Error 01

deebatman316 — Mon, 30 Jun 2025 16:05:30 GMT

Does the camera show an aperture set or does it say F/00 or F/—. If it does for some reason the camera and lens aren’t communicating. Do other lenses work properly on that camera. That lens utilizes an electronic focus ring so if the camera and lens can’t communicate manually focus doesn’t work either. All the focus ring is connected to is a digital encoder. When you turn the focus ring with the camera set to One Shot AF. The lens sends a signal to the camera which way you’re turning the focus ring. Then the camera sends a signal back to the lens to tell the AF motor to carry out manual focusing.

Re: EOS 90D Error 01

ken002 — Mon, 30 Jun 2025 16:17:12 GMT

Re: EOS 90D Error 01

deebatman316 — Mon, 30 Jun 2025 16:25:45 GMT

Set the aperture to a small number such as F/11 or F/16. Then press the depth of field preview button. The lens should stop down to the selected aperture. If Error 1 pops back up it’s a lens problem. By default the lens aperture stays open when focusing and composing your shot. It stops down before the picture is taken.

Re: EOS 90D Error 01

ken002 — Mon, 30 Jun 2025 16:37:46 GMT

Awesome. It seems to be working now. Thanks so much!!

Re: EOS 90D Error 01

deebatman316 — Mon, 30 Jun 2025 16:41:58 GMT

Note this is not a fix. You likely have a failing aperture motor, flex cable or sticky aperture blades that aren’t always stopping down. Newer cameras utilize faster communication speeds between the lens and camera. Older lenses with failing flex cables make work fine on an older. But on a new one it could cause problems.

Re: EOS 90D Error 01

ken002 — Mon, 30 Jun 2025 16:44:00 GMT

This is the lens that came with the body, so they should be the same.

Re: EOS 90D Error 01

deebatman316 — Mon, 30 Jun 2025 17:38:48 GMT

Not really it depends on the release date of the lens. Canon makes lenses in batches and when they sell out they make a new batch or just discontinue it. The EOS 90D was released after that lens. So even if a lens came new with the camera doesn’t mean the design is new. Canon often sells very old versions of kit lenses today with Rebel series cameras. Despite newer versions of it available.