diff --git a/modules/swagger-codegen/src/main/resources/php/api.mustache b/modules/swagger-codegen/src/main/resources/php/api.mustache
index a434699f90a..e0b94e6b232 100644
--- a/modules/swagger-codegen/src/main/resources/php/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/api.mustache
@@ -39,6 +39,12 @@ class {{classname}} {
 {{/allParams}}   * @return {{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}void{{/returnType}}
    */
    public function {{nickname}}({{#allParams}}${{paramName}}{{#optional}}=null{{/optional}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) {
+      {{#allParams}}{{#required}}
+      // verify the required parameter '{{paramName}}' is set
+      if (${{paramName}} === null) {
+        throw new \Exception("Missing the required parameter ${{paramName}} when calling {{nickname}}");
+      }
+      {{/required}}{{/allParams}}
 
       // parse inputs
       $resourcePath = "{{path}}";
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/PetApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/PetApi.php
index 80d9c040d1e..fc8331da4bd 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/PetApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/PetApi.php
@@ -38,6 +38,7 @@ class PetApi {
    * @return void
    */
    public function updatePet($body) {
+      
 
       // parse inputs
       $resourcePath = "/pet";
@@ -91,6 +92,7 @@ class PetApi {
    * @return void
    */
    public function addPet($body) {
+      
 
       // parse inputs
       $resourcePath = "/pet";
@@ -144,6 +146,7 @@ class PetApi {
    * @return array[Pet]
    */
    public function findPetsByStatus($status) {
+      
 
       // parse inputs
       $resourcePath = "/pet/findByStatus";
@@ -202,6 +205,7 @@ class PetApi {
    * @return array[Pet]
    */
    public function findPetsByTags($tags) {
+      
 
       // parse inputs
       $resourcePath = "/pet/findByTags";
@@ -260,6 +264,12 @@ class PetApi {
    * @return Pet
    */
    public function getPetById($pet_id) {
+      
+      // verify the required parameter 'pet_id' is set
+      if ($pet_id === null) {
+        throw new \Exception("Missing the required parameter $pet_id when calling getPetById");
+      }
+      
 
       // parse inputs
       $resourcePath = "/pet/{petId}";
@@ -321,6 +331,12 @@ class PetApi {
    * @return void
    */
    public function updatePetWithForm($pet_id, $name, $status) {
+      
+      // verify the required parameter 'pet_id' is set
+      if ($pet_id === null) {
+        throw new \Exception("Missing the required parameter $pet_id when calling updatePetWithForm");
+      }
+      
 
       // parse inputs
       $resourcePath = "/pet/{petId}";
@@ -381,6 +397,12 @@ class PetApi {
    * @return void
    */
    public function deletePet($api_key, $pet_id) {
+      
+      // verify the required parameter 'pet_id' is set
+      if ($pet_id === null) {
+        throw new \Exception("Missing the required parameter $pet_id when calling deletePet");
+      }
+      
 
       // parse inputs
       $resourcePath = "/pet/{petId}";
@@ -439,6 +461,12 @@ class PetApi {
    * @return void
    */
    public function uploadFile($pet_id, $additional_metadata, $file) {
+      
+      // verify the required parameter 'pet_id' is set
+      if ($pet_id === null) {
+        throw new \Exception("Missing the required parameter $pet_id when calling uploadFile");
+      }
+      
 
       // parse inputs
       $resourcePath = "/pet/{petId}/uploadImage";
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/StoreApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/StoreApi.php
index 4e40ed983b9..6e3ce56e7ce 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/StoreApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/StoreApi.php
@@ -37,6 +37,7 @@ class StoreApi {
    * @return map[string,int]
    */
    public function getInventory() {
+      
 
       // parse inputs
       $resourcePath = "/store/inventory";
@@ -92,6 +93,7 @@ class StoreApi {
    * @return Order
    */
    public function placeOrder($body) {
+      
 
       // parse inputs
       $resourcePath = "/store/order";
@@ -151,6 +153,12 @@ class StoreApi {
    * @return Order
    */
    public function getOrderById($order_id) {
+      
+      // verify the required parameter 'order_id' is set
+      if ($order_id === null) {
+        throw new \Exception("Missing the required parameter $order_id when calling getOrderById");
+      }
+      
 
       // parse inputs
       $resourcePath = "/store/order/{orderId}";
@@ -210,6 +218,12 @@ class StoreApi {
    * @return void
    */
    public function deleteOrder($order_id) {
+      
+      // verify the required parameter 'order_id' is set
+      if ($order_id === null) {
+        throw new \Exception("Missing the required parameter $order_id when calling deleteOrder");
+      }
+      
 
       // parse inputs
       $resourcePath = "/store/order/{orderId}";
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/UserApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/UserApi.php
index f3e9e7f4cc6..8296d5e92fd 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/UserApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/UserApi.php
@@ -38,6 +38,7 @@ class UserApi {
    * @return void
    */
    public function createUser($body) {
+      
 
       // parse inputs
       $resourcePath = "/user";
@@ -91,6 +92,7 @@ class UserApi {
    * @return void
    */
    public function createUsersWithArrayInput($body) {
+      
 
       // parse inputs
       $resourcePath = "/user/createWithArray";
@@ -144,6 +146,7 @@ class UserApi {
    * @return void
    */
    public function createUsersWithListInput($body) {
+      
 
       // parse inputs
       $resourcePath = "/user/createWithList";
@@ -198,6 +201,7 @@ class UserApi {
    * @return string
    */
    public function loginUser($username, $password) {
+      
 
       // parse inputs
       $resourcePath = "/user/login";
@@ -258,6 +262,7 @@ class UserApi {
    * @return void
    */
    public function logoutUser() {
+      
 
       // parse inputs
       $resourcePath = "/user/logout";
@@ -307,6 +312,12 @@ class UserApi {
    * @return User
    */
    public function getUserByName($username) {
+      
+      // verify the required parameter 'username' is set
+      if ($username === null) {
+        throw new \Exception("Missing the required parameter $username when calling getUserByName");
+      }
+      
 
       // parse inputs
       $resourcePath = "/user/{username}";
@@ -367,6 +378,12 @@ class UserApi {
    * @return void
    */
    public function updateUser($username, $body) {
+      
+      // verify the required parameter 'username' is set
+      if ($username === null) {
+        throw new \Exception("Missing the required parameter $username when calling updateUser");
+      }
+      
 
       // parse inputs
       $resourcePath = "/user/{username}";
@@ -424,6 +441,12 @@ class UserApi {
    * @return void
    */
    public function deleteUser($username) {
+      
+      // verify the required parameter 'username' is set
+      if ($username === null) {
+        throw new \Exception("Missing the required parameter $username when calling deleteUser");
+      }
+      
 
       // parse inputs
       $resourcePath = "/user/{username}";