ERR 01
Canon DSLR Camera
Severity: ModerateWhat Does This Error Mean?
ERR 01 means the camera and lens cannot communicate properly. The electrical contacts between the camera body and the lens are not making a good connection. Clean the gold contacts on both the lens and the camera body.
Affected Models
- Canon EOS Rebel series
- Canon EOS 5D
- Canon EOS 6D
- Canon EOS 90D
- Canon EOS R series (with EF adapter)
- Most Canon EF/EF-S mount cameras
Common Causes
- Dirty or corroded lens contacts
- Lens not fully seated on the camera body
- Third-party lens with incompatible firmware
- Bent contact pin on the camera body
- Lens internal electronics failure
How to Fix It
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Remove the lens and clean the gold contacts on both lens and body.
Use a microfiber cloth or pencil eraser. Do not use liquid cleaners — they can damage the contacts.
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Reattach the lens firmly — twist until it clicks.
A loose lens does not make full contact. Make sure the red or white dot aligns and the lens clicks into place.
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Try a different lens to isolate the problem.
If ERR 01 only appears with one lens, that lens needs service. If all lenses trigger it, the camera body contacts need inspection.
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For third-party lenses: check for firmware updates from the lens manufacturer.
Sigma, Tamron, and other brands release firmware updates for lens compatibility. Sigma offers a USB dock for updating lens firmware.
Frequently Asked Questions
Can I use the camera without a lens?
You can access menus and playback, but you cannot take photos without a lens (unless you enable live view in certain modes).
Do EF lenses work on Canon mirrorless bodies?
Yes, with the Canon EF-EOS R adapter. ERR 01 can sometimes occur if the adapter contacts are dirty — clean them too.