Per default, gnupg uses its own CCID driver, not pcscd. If the card is detected by pcscd, gnupg can no longer access it. There are two solutions:
- Instruct GnuPG to use pcscd by adding
disable-ccid
to~/.gnupg/scdaemon.conf
and restart scdaemon withgpg-connect-agent 'SCD KILLSCD' /bye
- Stop pcscd and re-connect the device (make sure that pcscd is not activated again by a socket or similar)
See this guide for more information: Ludovic Rousseau's blog: GnuPG and PC/SC conflicts