This is most likely the snap strict confinement that prevents communication with the serial device. Can you please run the following command in a terminal, then run chromium and reproduce the problem, and share the output of the terminal here?
journalctl -f | grep chromium ** Changed in: chromium-browser (Ubuntu) Status: New => Incomplete ** Summary changed: - Web Serial fails to access local device + [snap] Web Serial fails to access local device ** Tags added: snap -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1890365 Title: [snap] Web Serial fails to access local device To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/chromium-browser/+bug/1890365/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs