diff --git a/tripleoclient/tests/v1/undercloud/test_config.py b/tripleoclient/tests/v1/undercloud/test_config.py
index 624b43792..5ec75ee4e 100644
--- a/tripleoclient/tests/v1/undercloud/test_config.py
+++ b/tripleoclient/tests/v1/undercloud/test_config.py
@@ -874,6 +874,26 @@ class TestNetworkSettings(base.TestCase):
         }
         self.assertEqual(expected, env)
 
+    def test_generate_inspection_subnets(self):
+        result = undercloud_config._generate_inspection_subnets()
+        expected = [{'gateway': '192.168.24.1',
+                     'host_routes': [],
+                     'ip_range': '192.168.24.100,192.168.24.120',
+                     'mtu': 1500,
+                     'netmask': '255.255.255.0',
+                     'tag': 'ctlplane-subnet'}]
+        self.assertEqual(expected, result)
+
+    def test_generate_inspection_subnets_invalid(self):
+        self.conf.config(subnets=['ctlplane-subnet', 'subnet1'])
+        self.conf.config(host_routes=[{'destination': '10.10.10.254/32',
+                                       'nexthop': '192.168.24.1'}],
+                         group='ctlplane-subnet')
+        self.conf.register_opts(self.opts, group=self.grp1)
+        self.conf.config(group='subnet1')
+        self.assertRaises(exceptions.DeploymentError,
+                          undercloud_config._generate_inspection_subnets)
+
 
 class TestTLSSettings(base.TestCase):
     def test_public_host_with_ip_should_give_ip_endpoint_environment(self):
diff --git a/tripleoclient/v1/undercloud_config.py b/tripleoclient/v1/undercloud_config.py
index 68140dcfd..3d94893cd 100644
--- a/tripleoclient/v1/undercloud_config.py
+++ b/tripleoclient/v1/undercloud_config.py
@@ -224,23 +224,30 @@ def _generate_inspection_subnets():
         env_dict = {}
         s = CONF.get(subnet)
         env_dict['tag'] = subnet
-        if netaddr.IPNetwork(s.cidr).version == 4:
-            env_dict['ip_range'] = s.inspection_iprange
-        if netaddr.IPNetwork(s.cidr).version == 6:
-            if CONF['ipv6_address_mode'] == 'dhcpv6-stateful':
+        try:
+            if netaddr.IPNetwork(s.cidr).version == 4:
                 env_dict['ip_range'] = s.inspection_iprange
-            if CONF['ipv6_address_mode'] == 'dhcpv6-stateless':
-                # dnsmasq(8): A static-only subnet with address all zeros may
-                # be used as a "catch-all" address to enable replies to all
-                # Information-request packets on a subnet which is provided
-                # with stateless DHCPv6, ie --dhcp-range=::,static
-                env_dict['ip_range'] = ','.join(
-                    [str(netaddr.IPNetwork(s.cidr).ip), 'static'])
-        env_dict['netmask'] = str(netaddr.IPNetwork(s.cidr).netmask)
-        env_dict['gateway'] = s.gateway
-        env_dict['host_routes'] = s.host_routes
-        env_dict['mtu'] = CONF.local_mtu
-        env_list.append(env_dict)
+            if netaddr.IPNetwork(s.cidr).version == 6:
+                if CONF['ipv6_address_mode'] == 'dhcpv6-stateful':
+                    env_dict['ip_range'] = s.inspection_iprange
+                if CONF['ipv6_address_mode'] == 'dhcpv6-stateless':
+                    # dnsmasq(8): A static-only subnet with address all zeros
+                    # may be used as a "catch-all" address to enable replies to
+                    # all Information-request packets on a subnet which is
+                    # provided with stateless DHCPv6, ie --dhcp-range=::,static
+                    env_dict['ip_range'] = ','.join(
+                        [str(netaddr.IPNetwork(s.cidr).ip), 'static'])
+            env_dict['netmask'] = str(netaddr.IPNetwork(s.cidr).netmask)
+            env_dict['gateway'] = s.gateway
+            env_dict['host_routes'] = s.host_routes
+            env_dict['mtu'] = CONF.local_mtu
+            env_list.append(env_dict)
+        except Exception as e:
+            msg = _('Invalid configuration data in subnet "{}". Double check '
+                    'the settings for this subnet. Error: {}').format(subnet,
+                                                                      e)
+            LOG.error(msg)
+            raise exceptions.DeploymentError(msg)
     return env_list