--- clientserver.c.orig	2015-08-24 20:54:00.000000000 +0200
+++ clientserver.c	2017-01-15 15:10:05.411549000 +0100
@@ -550,7 +550,7 @@
 		if (errno) {
 			rsyserr(FLOG, errno, "failed to open lock file %s",
 				lp_lock_file(i));
-			io_printf(f_out, "@ERROR: failed to open lock file\n");
+			io_printf(f_out, "@ERROR: failed to open lock file: %s (%d)\n", strerror(errno), errno);
 		} else {
 			rprintf(FLOG, "max connections (%d) reached\n",
 				lp_max_connections(i));