If you have multiple Canon apps installed, they may be fighting for control of the camera. Canon : Product Manual : EOS Utility : Troubleshooting
It is incredibly frustrating when you are halfway through offloading a day's worth of shots and the message pops up in Canon EOS Utility. This error usually stems from power management settings, faulty hardware connections, or software conflicts between various Canon background services. 1. Disable Auto Power Off
Connect the camera directly to a USB port on your computer rather than a USB hub or monitor port. eos utility the camera was disconnected during download
The most common "silent" cause of this error is the camera's internal timer. If the download takes longer than your camera's idle timeout, it will shut down and sever the connection.
Go to your camera's Setup Menu (the yellow wrench icon) and set Auto Power Off to [Disable] or [Off] before starting your transfer. 2. Check Physical Connections If you have multiple Canon apps installed, they
Move the cable to a different port (e.g., from a front panel port to a motherboard port on a PC) to force a fresh hardware handshake.
Even a micro-flicker in the connection can cause EOS Utility to abort the entire download. If the download takes longer than your camera's
Not all USB cables are "data" cables; some are "charging-only." Ensure you are using the original interface cable that came with your EOS camera. 3. Resolve Software Conflicts