GPG hangs on hostname change

I currently use GnuPG with Yubikeys, mostly (but not only) for pass.

One fine day I’ll switch to age (from FiloSottile; with SK and TPM) with passage, and other awesome stuff; but today it’s gpg.

Today that gpg (GnuPG) 2.4.3 suddenly stopped working, just stuck and hanging in there… I’ve debugged it with strace:

$ strace gpg --debug-all --card-status
(...)
openat(AT_FDCWD, "/etc/localtime", O_RDONLY|O_CLOEXEC) = 4
newfstatat(4, "", {st_mode=S_IFREG|0644, st_size=1909, ...}, AT_EMPTY_PATH) = 0
newfstatat(4, "", {st_mode=S_IFREG|0644, st_size=1909, ...}, AT_EMPTY_PATH) = 0
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\5\0\0\0\5\0\0\0\0"..., 4096) = 1909
lseek(4, -1217, SEEK_CUR)               = 692
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\6\0\0\0\6\0\0\0\0"..., 4096) = 1217
close(4)                                = 0
newfstatat(AT_FDCWD, "/run/user/1000/gnupg/S.keyboxd", {st_mode=S_IFSOCK|0700, st_size=0, ...}, 0) = 0
socket(AF_UNIX, SOCK_STREAM, 0)         = 4
newfstatat(AT_FDCWD, "/run/user/1000/gnupg/S.keyboxd", {st_mode=S_IFSOCK|0700, st_size=0, ...}, 0) = 0
connect(4, {sa_family=AF_UNIX, sun_path="/run/user/1000/gnupg/S.keyboxd"}, 32) = 0
recvmsg(4,

Turns out this is https://dev.gnupg.org/T6838, which I found after some research, via https://bugzilla.redhat.com/show_bug.cgi?id=2249218.

That bug mentions something related to lock files and hostname changes, and I had indeed changed it. What was quite confusing is that I had made that change a few days ago already; but the problem only surfaced today, after a reboot. Interestingly, changing the hostname back to what it used to be didn’t fix it (for me).

I didn’t try removing use-keyboxd from ~/.gnupg/common.conf (which some posts in some Forums recommend), because it wasn’t fully clear to me what that changes, breaks or not. I wasn’t super motivated to dig further into it, as I like stuff to “work with out of the box defaults”, when possible.

The “solution” what worked for me was just to rm -rf ~/.gnupg/ and start over; that’s easy with my dotfiles, for me. Of course, YMMV; if you’re reading this, you presumably are an adult who knows what you are doing; don’t blame me if you inadvertently loose your private keys by removing that directory!