Err 01, Canon
What it means, in 6 of the 8 we read: Communication failure between camera and lens. What to do: it depends on the model; find yours below.
Still seeing Err 01?
Clean the electrical contacts on the camera and on the lens again, gently, with a soft cloth. The manuals' care notes say not to touch the contacts with your fingers, since that can corrode them, not to use cleaners that contain organic solvents, and to take care not to scratch the lens glass.
Turn the camera off and on again, or take the battery out and put it back in; several of the manuals listed here give this as a fix.
Try another Canon lens; most of the manuals listed here say to use a Canon lens.
Our reasoning, not the source's: If only one lens brings up the message, the fault most likely lies with that lens; if every lens does, it most likely lies with the camera.
If it keeps appearing, write down the error number and contact a Canon Service Center, as the manuals say to do when an error persists.
In the 8 we read
| Camera | What it means† | What to do† | What its manual also says† |
|---|---|---|---|
| Canon EOS 50D | Communication failure between camera and lens. | Clean contacts on both devices, use a Canon lens, or get professional repair. | If errors persist, note the code and contact Canon Service. Restart or reinsert battery to recover. Do not touch contacts with fingers or use solvent cleaners. |
| Canon EOS 5D | Communication failure between the camera body and the attached lens. | Clean the contacts on the lens. | If the error repeats, write down the code and visit a Canon Service Center. Check if the photo was saved by pressing the display button. Do not touch electrical contacts with fingers and avoid cleaners with organic solvents. |
| Canon EOS 5D Mark III | Communication failure between camera and lens. | Clean camera and lens electrical contacts, or use a Canon lens. | Same as “What the manuals also say” below |
| Canon EOS 5D Mark IV | Communication failure between camera and lens. | Clean contacts, use a Canon lens, or remove and reinsert the battery. | If the error continues, note the code and contact Canon Service. Do not touch contacts with fingers. Avoid cleaners with organic solvents. |
| Canon EOS 60D | Communication failure between camera and lens. | Clean the electrical contacts on both the camera and the lens, and ensure a Canon lens is attached. | Same as “What the manuals also say” below |
| Canon EOS 760D | Communication failure between camera and lens. | Clean contacts, use a Canon lens, or remove and reinsert the battery. | Same as “What the manuals also say” below |
| Canon EOS 7D | Communication between camera and lens is faulty. | Clean camera and lens electrical contacts, or use a Canon lens. | Same as “What the manuals also say” below |
| Canon EOS 7D Mark II | Communication failure between camera and lens. | Clean contacts, use a Canon lens, or remove and reinsert the battery. | If the error continues, record the number and contact Canon Service. Restarting or reseating the battery is advised for some errors. Clean lens contacts if communication fails. |
What the manuals also say
- If the error persists, write down the number and contact Canon Service. Do not touch electrical contacts with fingers. Do not use cleaners with organic solvents (Canon EOS 5D Mark III, Canon EOS 60D, Canon EOS 760D and Canon EOS 7D).
Other Canon messages
Sources
- Canon camera instruction manuals (PDF), one per model, checked Oct 6, 2026
Each value is checked automatically against the source it links, on the date shown. How we build these pages
† What it means and What to do and What its manual also says: restated in plain words from the sources linked here; each source has the exact wording.