ERR 01
Canon DSLR Camera
Severity: ModerateWhat it means
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
-
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. -
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. -
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. -
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.