Networked Home broken
Should you run into the following problem:
gpg: lock not made: link() failed: Operation not supported
gpg: can't lock
you have to add the following line to your gpg.conf which is usually located at ~/.gnupg
This disables locking entirely.
In case this doesn't solve your problem, please open System Preferences > GPGPreferences / GPG Suite > Send Report.
Please open Terminal and copy the output of the following two commands into your report:
cat ~/.gnupg/gpg.conf cat ~/.gnupg/gpg-agent.conf