Device Connect When Calibre is Running

gussy · 04-09-2026, 11:34 AM

When Calibre is already open and a device is then connected via USB, Calibre sometimes fails to detect it. Currently the only workaround is to close and reopen Calibre entirely. A "Rescan for devices" button (or menu option under Device menu) would trigger the same device polling that happens at startup, allowing users to force detection without restarting. This is especially useful for USB devices connected after launch.

kovidgoyal · 04-09-2026, 12:12 PM

On what OS and what device. And there is no special polling that happens at startup. there is only one typeof polling and it is done continuously. Most likely your device is being extra slow to reach a working state. The device open code in calibre gives up after a few seconds if the device fails ot open. You can run calibre in debug mode and you will see it happening.

04-09-2026, 11:34 AM	#1
gussy Member Posts: 14 Karma: 10 Join Date: Dec 2019 Device: Galaxy S26 Ultra	Device Connect When Calibre is Running When Calibre is already open and a device is then connected via USB, Calibre sometimes fails to detect it. Currently the only workaround is to close and reopen Calibre entirely. A "Rescan for devices" button (or menu option under Device menu) would trigger the same device polling that happens at startup, allowing users to force detection without restarting. This is especially useful for USB devices connected after launch.

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04-09-2026, 12:12 PM	#2
kovidgoyal creator of calibre Posts: 46,185 Karma: 29626604 Join Date: Oct 2006 Location: Mumbai, India Device: Various	On what OS and what device. And there is no special polling that happens at startup. there is only one typeof polling and it is done continuously. Most likely your device is being extra slow to reach a working state. The device open code in calibre gives up after a few seconds if the device fails ot open. You can run calibre in debug mode and you will see it happening.

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