diff --git a/app/code/Magento/Checkout/etc/adminhtml/system.xml b/app/code/Magento/Checkout/etc/adminhtml/system.xml
index 11e3ba5f3ed9a..2afa796443e75 100644
--- a/app/code/Magento/Checkout/etc/adminhtml/system.xml
+++ b/app/code/Magento/Checkout/etc/adminhtml/system.xml
@@ -27,12 +27,14 @@
                 </field>
                 <field id="max_items_display_count" translate="label" type="text" sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Maximum Number of Items to Display in Order Summary</label>
+                    <validate>validate-zero-or-greater validate-digits</validate>
                 </field>
             </group>
             <group id="cart" translate="label" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Shopping Cart</label>
                 <field id="delete_quote_after" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="0" canRestore="1">
                     <label>Quote Lifetime (days)</label>
+                    <validate>validate-zero-or-greater validate-digits</validate>
                 </field>
                 <field id="redirect_to_cart" translate="label" type="select" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>After Adding a Product Redirect to Shopping Cart</label>
@@ -40,6 +42,7 @@
                 </field>
                 <field id="number_items_to_display_pager" translate="label" type="text" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Number of Items to Display Pager</label>
+                    <validate>validate-zero-or-greater validate-digits</validate>
                 </field>
                 <field id="crosssell_enabled" translate="label" type="select" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Show Cross-sell Items in the Shopping Cart</label>
@@ -61,9 +64,11 @@
                 </field>
                 <field id="count" translate="label" type="text" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Number of Items to Display Scrollbar</label>
+                    <validate>validate-zero-or-greater validate-digits</validate>
                 </field>
                 <field id="max_items_display_count" translate="label" type="text" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Maximum Number of Items to Display</label>
+                    <validate>validate-zero-or-greater validate-digits</validate>
                 </field>
             </group>
             <group id="payment_failed" translate="label" type="text" sortOrder="100" showInDefault="1" showInWebsite="1" showInStore="1">
@@ -83,6 +88,7 @@
                 </field>
                 <field id="copy_to" translate="label comment" type="text" sortOrder="4" showInDefault="1" showInWebsite="1" showInStore="1">
                     <label>Send Payment Failed Email Copy To</label>
+                    <validate>validate-emails</validate>
                     <comment>Separate by ",".</comment>
                 </field>
                 <field id="copy_method" translate="label" type="select" sortOrder="5" showInDefault="1" showInWebsite="1" showInStore="1">
diff --git a/app/code/Magento/Paypal/etc/adminhtml/system/express_checkout.xml b/app/code/Magento/Paypal/etc/adminhtml/system/express_checkout.xml
index d5287659ee7d2..04d5fae435816 100644
--- a/app/code/Magento/Paypal/etc/adminhtml/system/express_checkout.xml
+++ b/app/code/Magento/Paypal/etc/adminhtml/system/express_checkout.xml
@@ -117,13 +117,15 @@
                         <field id="use_proxy">1</field>
                     </depends>
                 </field>
-                <field id="proxy_port" translate="label" type="text" sortOrder="110" showInDefault="1" showInWebsite="1">
+                <field id="proxy_port" translate="label comment" type="text" sortOrder="110" showInDefault="1" showInWebsite="1">
                     <label>Proxy Port</label>
+                    <comment>Please enter at least 0 and at most 65535</comment>
                     <config_path>paypal/wpp/proxy_port</config_path>
                     <attribute type="shared">1</attribute>
                     <depends>
                         <field id="use_proxy">1</field>
                     </depends>
+                    <validate>validate-digits validate-digits-range digits-range-0-65535</validate>
                 </field>
             </group>
             <field id="enable_express_checkout" translate="label" type="select" sortOrder="20" showInDefault="1" showInWebsite="1">
@@ -348,6 +350,7 @@
                 <depends>
                     <field id="payment_action">Order</field>
                 </depends>
+                <validate>validate-zero-or-greater validate-digits</validate>
             </field>
             <field id="order_valid_period" translate="label comment" type="text" sortOrder="60" showInDefault="1" showInWebsite="1">
                 <label>Order Valid Period (days)</label>
@@ -357,6 +360,7 @@
                 <depends>
                     <field id="payment_action">Order</field>
                 </depends>
+                <validate>validate-zero-or-greater validate-digits</validate>
             </field>
             <field id="child_authorization_number" translate="label comment" type="text" sortOrder="70" showInDefault="1" showInWebsite="1">
                 <label>Number of Child Authorizations</label>
diff --git a/app/code/Magento/Paypal/etc/adminhtml/system/payflow_advanced.xml b/app/code/Magento/Paypal/etc/adminhtml/system/payflow_advanced.xml
index cba36916c3305..1ae0b52146c38 100644
--- a/app/code/Magento/Paypal/etc/adminhtml/system/payflow_advanced.xml
+++ b/app/code/Magento/Paypal/etc/adminhtml/system/payflow_advanced.xml
@@ -69,13 +69,15 @@
                     </depends>
                     <attribute type="shared">1</attribute>
                 </field>
-                <field id="proxy_port" translate="label" type="text" sortOrder="90" showInDefault="1" showInWebsite="1">
+                <field id="proxy_port" translate="label comment" type="text" sortOrder="90" showInDefault="1" showInWebsite="1">
                     <label>Proxy Port</label>
+                    <comment>Please enter at least 0 and at most 65535</comment>
                     <config_path>payment/payflow_advanced/proxy_port</config_path>
                     <depends>
                         <field id="use_proxy">1</field>
                     </depends>
                     <attribute type="shared">1</attribute>
+                    <validate>validate-digits validate-digits-range digits-range-0-65535</validate>
                 </field>
                 <field id="payflow_advanced_info" showInDefault="1" showInWebsite="1" showInStore="1" sortOrder="100">
                     <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Payflowlink\Advanced</frontend_model>
diff --git a/app/code/Magento/Paypal/etc/adminhtml/system/payflow_link.xml b/app/code/Magento/Paypal/etc/adminhtml/system/payflow_link.xml
index ed11e8ba18d07..ead70eca3fadd 100644
--- a/app/code/Magento/Paypal/etc/adminhtml/system/payflow_link.xml
+++ b/app/code/Magento/Paypal/etc/adminhtml/system/payflow_link.xml
@@ -70,13 +70,15 @@
                     </depends>
                     <attribute type="shared">1</attribute>
                 </field>
-                <field id="proxy_port" translate="label" type="text" sortOrder="80" showInDefault="1" showInWebsite="1">
+                <field id="proxy_port" translate="label comment" type="text" sortOrder="80" showInDefault="1" showInWebsite="1">
                     <label>Proxy Port</label>
+                    <comment>Please enter at least 0 and at most 65535</comment>
                     <config_path>payment/payflow_link/proxy_port</config_path>
                     <depends>
                         <field id="use_proxy">1</field>
                     </depends>
                     <attribute type="shared">1</attribute>
+                    <validate>validate-digits validate-digits-range digits-range-0-65535</validate>
                 </field>
                 <field id="payflowlink_info" showInDefault="1" showInWebsite="1" showInStore="1" sortOrder="90">
                     <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Payflowlink\Info</frontend_model>
diff --git a/app/code/Magento/Paypal/etc/adminhtml/system/paypal_payflowpro.xml b/app/code/Magento/Paypal/etc/adminhtml/system/paypal_payflowpro.xml
index e5a0319bdc1bf..c87a781f36c00 100644
--- a/app/code/Magento/Paypal/etc/adminhtml/system/paypal_payflowpro.xml
+++ b/app/code/Magento/Paypal/etc/adminhtml/system/paypal_payflowpro.xml
@@ -65,13 +65,15 @@
                     </depends>
                     <attribute type="shared">1</attribute>
                 </field>
-                <field id="proxy_port" translate="label" type="text" sortOrder="90" showInDefault="1" showInWebsite="1">
+                <field id="proxy_port" translate="label comment" type="text" sortOrder="90" showInDefault="1" showInWebsite="1">
                     <label>Proxy Port</label>
+                    <comment>Please enter at least 0 and at most 65535</comment>
                     <config_path>payment/payflowpro/proxy_port</config_path>
                     <depends>
                         <field id="use_proxy">1</field>
                     </depends>
                     <attribute type="shared">1</attribute>
+                    <validate>validate-digits validate-digits-range digits-range-0-65535</validate>
                 </field>
             </group>
             <field id="enable_paypal_payflow" translate="label" type="select" sortOrder="20" showInDefault="1" showInWebsite="1">
diff --git a/app/code/Magento/Paypal/i18n/en_US.csv b/app/code/Magento/Paypal/i18n/en_US.csv
index e7264a6de807f..4e47c4c1f9e9f 100644
--- a/app/code/Magento/Paypal/i18n/en_US.csv
+++ b/app/code/Magento/Paypal/i18n/en_US.csv
@@ -737,3 +737,4 @@ User,User
 "PayPal Credit","PayPal Credit"
 "PayPal Guest Checkout Credit Card Icons","PayPal Guest Checkout Credit Card Icons"
 "Elektronisches Lastschriftverfahren - German ELV","Elektronisches Lastschriftverfahren - German ELV"
+"Please enter at least 0 and at most 65535","Please enter at least 0 and at most 65535"