As @theducks said, that is coming from the Kobo Utilities plugin. And is probably being caused by having the "Configure options for each device" selected, but not actually having one of the devices configured. I'm fairly sure I can see where it is happening, but, if you see it again, can you copy details and post them?
Fix it is probably as simple as going to the second tab of the plugin configuration, selecting the Aura ONE and then configuring the option below it. Or turning off the "Configure options for each device" and using the same configuration for all the devices.
But, this shouldn't be affecting sending books to the device. These are unrelated functions. The error should be happening during when the device is connected after the book list has been retrieved. It shouldn't be blocking any of the actions for sending the books. I think something else is happening. Can you try running calibre in debug mode and posting the log? Maybe something will be obvious in the log.
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