diff --git a/extras/add_vpn_user.sh b/extras/add_vpn_user.sh
index a142b61..aadad2a 100644
--- a/extras/add_vpn_user.sh
+++ b/extras/add_vpn_user.sh
@@ -2,7 +2,7 @@
 #
 # Script to add/update an VPN user for both IPsec/L2TP and Cisco IPsec
 #
-# Copyright (C) 2018-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2018-2020 Lin Song <linsongui@gmail.com>
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/
diff --git a/extras/del_vpn_user.sh b/extras/del_vpn_user.sh
index 514b2d6..ee0249e 100644
--- a/extras/del_vpn_user.sh
+++ b/extras/del_vpn_user.sh
@@ -2,7 +2,7 @@
 #
 # Script to delete an VPN user for both IPsec/L2TP and Cisco IPsec
 #
-# Copyright (C) 2018-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2018-2020 Lin Song <linsongui@gmail.com>
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/
diff --git a/extras/update_vpn_users.sh b/extras/update_vpn_users.sh
index 0df05da..93ec63b 100644
--- a/extras/update_vpn_users.sh
+++ b/extras/update_vpn_users.sh
@@ -2,7 +2,7 @@
 #
 # Script to update VPN users for both IPsec/L2TP and Cisco IPsec
 #
-# Copyright (C) 2018-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2018-2020 Lin Song <linsongui@gmail.com>
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/
diff --git a/extras/vpnupgrade.sh b/extras/vpnupgrade.sh
index f7c408f..dcaae74 100644
--- a/extras/vpnupgrade.sh
+++ b/extras/vpnupgrade.sh
@@ -2,7 +2,7 @@
 #
 # Script to upgrade Libreswan on Ubuntu and Debian
 #
-# Copyright (C) 2016-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2016-2020 Lin Song <linsongui@gmail.com>
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/
@@ -28,7 +28,9 @@ if [ -z "$os_type" ]; then
   [ -f /etc/lsb-release ] && os_type=$(. /etc/lsb-release && printf '%s' "$DISTRIB_ID")
 fi
 if ! printf '%s' "$os_type" | head -n 1 | grep -qiF -e ubuntu -e debian -e raspbian; then
-  exiterr "This script only supports Ubuntu and Debian."
+  echo "Error: This script only supports Ubuntu and Debian." >&2
+  echo "For CentOS/RHEL, use https://git.io/vpnupgrade-centos" >&2
+  exit 1
 fi
 
 if [ "$(sed 's/\..*//' /etc/debian_version)" = "7" ]; then
diff --git a/extras/vpnupgrade_centos.sh b/extras/vpnupgrade_centos.sh
index 5f494e3..202a2e1 100644
--- a/extras/vpnupgrade_centos.sh
+++ b/extras/vpnupgrade_centos.sh
@@ -2,7 +2,7 @@
 #
 # Script to upgrade Libreswan on CentOS and RHEL
 #
-# Copyright (C) 2016-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2016-2020 Lin Song <linsongui@gmail.com>
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/
@@ -23,7 +23,9 @@ exiterr2() { exiterr "'yum install' failed."; }
 vpnupgrade() {
 
 if ! grep -qs -e "release 6" -e "release 7" -e "release 8" /etc/redhat-release; then
-  exiterr "This script only supports CentOS/RHEL 6, 7 and 8."
+  echo "Error: This script only supports CentOS/RHEL 6, 7 and 8." >&2
+  echo "For Ubuntu/Debian, use https://git.io/vpnupgrade" >&2
+  exit 1
 fi
 
 if [ -f /proc/user_beancounters ]; then
diff --git a/vpnsetup.sh b/vpnsetup.sh
index d6cf046..6c95f7d 100755
--- a/vpnsetup.sh
+++ b/vpnsetup.sh
@@ -8,7 +8,7 @@
 # The latest version of this script is available at:
 # https://github.com/hwdsl2/setup-ipsec-vpn
 #
-# Copyright (C) 2014-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2014-2020 Lin Song <linsongui@gmail.com>
 # Based on the work of Thomas Sarlandie (Copyright 2012)
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
@@ -54,7 +54,9 @@ if [ -z "$os_type" ]; then
   [ -f /etc/lsb-release ] && os_type=$(. /etc/lsb-release && printf '%s' "$DISTRIB_ID")
 fi
 if ! printf '%s' "$os_type" | head -n 1 | grep -qiF -e ubuntu -e debian -e raspbian; then
-  exiterr "This script only supports Ubuntu and Debian."
+  echo "Error: This script only supports Ubuntu and Debian." >&2
+  echo "For CentOS/RHEL, use https://git.io/vpnsetup-centos" >&2
+  exit 1
 fi
 
 if [ "$(sed 's/\..*//' /etc/debian_version)" = "7" ]; then
diff --git a/vpnsetup_centos.sh b/vpnsetup_centos.sh
index b0ab813..29904c2 100755
--- a/vpnsetup_centos.sh
+++ b/vpnsetup_centos.sh
@@ -8,7 +8,7 @@
 # The latest version of this script is available at:
 # https://github.com/hwdsl2/setup-ipsec-vpn
 #
-# Copyright (C) 2015-2019 Lin Song <linsongui@gmail.com>
+# Copyright (C) 2015-2020 Lin Song <linsongui@gmail.com>
 # Based on the work of Thomas Sarlandie (Copyright 2012)
 #
 # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
@@ -49,7 +49,9 @@ check_ip() {
 vpnsetup() {
 
 if ! grep -qs -e "release 6" -e "release 7" -e "release 8" /etc/redhat-release; then
-  exiterr "This script only supports CentOS/RHEL 6, 7 and 8."
+  echo "Error: This script only supports CentOS/RHEL 6, 7 and 8." >&2
+  echo "For Ubuntu/Debian, use https://git.io/vpnsetup" >&2
+  exit 1
 fi
 
 if [ -f /proc/user_beancounters ]; then