Remove the default keyserver.

NEWS

@@ -19,6 +19,7 @@ Noteworthy changes in version 2.5.3 (unreleased)
     renamed to --deprecated-supervised as preparation for their
     removal.  [rGa019a0fcd8]
 
+  * There is no more default for a keyserver.
 
   See-also: gnupg-announce/2024q4/000xxx.html
   Release-info: https://dev.gnupg.org/T7442

configure.ac

@@ -1930,7 +1930,7 @@ AC_DEFINE_UNQUOTED(TPM2DAEMON_SOCK_NAME, "S.tpm2daemon",
 AC_DEFINE_UNQUOTED(DIRMNGR_SOCK_NAME, "S.dirmngr",
                    [The name of the dirmngr socket])
 AC_DEFINE_UNQUOTED(DIRMNGR_DEFAULT_KEYSERVER,
-                   "hkps://keyserver.ubuntu.com",
+                   "hkps://none",
       [The default keyserver for dirmngr to use, if none is explicitly given])
 
 AC_DEFINE_UNQUOTED(GPGEXT_GPG, "gpg", [The standard binary file suffix])

dirmngr/server.c

@@ -2209,8 +2209,10 @@ ensure_keyserver (ctrl_t ctrl)
   if (!opt.keyserver)
     {
       /* No global option set.  Fall back to default:  */
-      return make_keyserver_item (DIRMNGR_DEFAULT_KEYSERVER,
-                                  &ctrl->server_local->keyservers);
+      /* return make_keyserver_item (DIRMNGR_DEFAULT_KEYSERVER, */
+      /*                             &ctrl->server_local->keyservers); */
+      err = gpg_error (GPG_ERR_NO_KEYSERVER);  /* No more default.  */
+      goto leave;
     }
 
   for (sl = opt.keyserver; sl; sl = sl->next)

doc/dirmngr.texi

@@ -345,9 +345,7 @@ service (.onion), Dirmngr selects the keyserver to use depending on
 whether Tor is locally running or not.  The check for a running Tor is
 done for each new connection.
 
-If no keyserver is explicitly configured, dirmngr will use the
-built-in default of @code{https://keyserver.ubuntu.com}.  To avoid the
-use of a default keyserver the value @code{none} can be used.
+There is no default keyserver since version 2.5.3.
 
 Windows users with a keyserver running on their Active Directory
 may use the short form @code{ldap:///} for @var{name} to access this directory.