diff --git a/samples/client/petstore/javascript-promise/docs/FakeApi.md b/samples/client/petstore/javascript-promise/docs/FakeApi.md
index b3bc1ae145f..24aca3b719b 100644
--- a/samples/client/petstore/javascript-promise/docs/FakeApi.md
+++ b/samples/client/petstore/javascript-promise/docs/FakeApi.md
@@ -87,7 +87,8 @@ var opts = {
   'binary': "B", // String | None
   '_date': new Date("2013-10-20"), // Date | None
   'dateTime': new Date("2013-10-20T19:20:30+01:00"), // Date | None
-  'password': "password_example" // String | None
+  'password': "password_example", // String | None
+  'callback': "callback_example" // String | None
 };
 apiInstance.testEndpointParameters(_number, _double, patternWithoutDelimiter, _byte, opts).then(function() {
   console.log('API called successfully.');
@@ -114,6 +115,7 @@ Name | Type | Description  | Notes
  **_date** | **Date**| None | [optional] 
  **dateTime** | **Date**| None | [optional] 
  **password** | **String**| None | [optional] 
+ **callback** | **String**| None | [optional] 
 
 ### Return type
 
diff --git a/samples/client/petstore/javascript-promise/src/ApiClient.js b/samples/client/petstore/javascript-promise/src/ApiClient.js
index b3d66a68174..56de9dddbdb 100644
--- a/samples/client/petstore/javascript-promise/src/ApiClient.js
+++ b/samples/client/petstore/javascript-promise/src/ApiClient.js
@@ -65,8 +65,8 @@
      */
     this.authentications = {
       'api_key': {type: 'apiKey', 'in': 'header', name: 'api_key'},
-      'http_basic_test': {type: 'basic'}
-      'petstore_auth': {type: 'oauth2'},
+      'http_basic_test': {type: 'basic'},
+      'petstore_auth': {type: 'oauth2'}
     };
     /**
      * The default HTTP headers to be included for all API calls.
@@ -368,7 +368,10 @@
 
     var contentType = this.jsonPreferredMime(contentTypes);
     if (contentType) {
-      request.type(contentType);
+      // Issue with superagent and multipart/form-data (https://github.com/visionmedia/superagent/issues/746)
+      if(contentType != 'multipart/form-data') {
+        request.type(contentType);
+      }
     } else if (!request.header['Content-Type']) {
       request.type('application/json');
     }
diff --git a/samples/client/petstore/javascript-promise/src/api/FakeApi.js b/samples/client/petstore/javascript-promise/src/api/FakeApi.js
index c4b4a1d8771..80ee81d5e34 100644
--- a/samples/client/petstore/javascript-promise/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/FakeApi.js
@@ -67,7 +67,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling testClientModel";
+        throw new Error("Missing the required parameter 'body' when calling testClientModel");
       }
 
 
@@ -110,6 +110,7 @@
      * @param {Date} opts._date None
      * @param {Date} opts.dateTime None
      * @param {String} opts.password None
+     * @param {String} opts.callback None
      * @return {Promise} a {@link https://www.promisejs.org/|Promise}
      */
     this.testEndpointParameters = function(_number, _double, patternWithoutDelimiter, _byte, opts) {
@@ -118,22 +119,22 @@
 
       // verify the required parameter '_number' is set
       if (_number == undefined || _number == null) {
-        throw "Missing the required parameter '_number' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_number' when calling testEndpointParameters");
       }
 
       // verify the required parameter '_double' is set
       if (_double == undefined || _double == null) {
-        throw "Missing the required parameter '_double' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_double' when calling testEndpointParameters");
       }
 
       // verify the required parameter 'patternWithoutDelimiter' is set
       if (patternWithoutDelimiter == undefined || patternWithoutDelimiter == null) {
-        throw "Missing the required parameter 'patternWithoutDelimiter' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter 'patternWithoutDelimiter' when calling testEndpointParameters");
       }
 
       // verify the required parameter '_byte' is set
       if (_byte == undefined || _byte == null) {
-        throw "Missing the required parameter '_byte' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_byte' when calling testEndpointParameters");
       }
 
 
@@ -156,7 +157,8 @@
         'binary': opts['binary'],
         'date': opts['_date'],
         'dateTime': opts['dateTime'],
-        'password': opts['password']
+        'password': opts['password'],
+        'callback': opts['callback']
       };
 
       var authNames = ['http_basic_test'];
diff --git a/samples/client/petstore/javascript-promise/src/api/PetApi.js b/samples/client/petstore/javascript-promise/src/api/PetApi.js
index 203b31905ed..d752a612bba 100644
--- a/samples/client/petstore/javascript-promise/src/api/PetApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/PetApi.js
@@ -68,7 +68,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling addPet";
+        throw new Error("Missing the required parameter 'body' when calling addPet");
       }
 
 
@@ -108,7 +108,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling deletePet";
+        throw new Error("Missing the required parameter 'petId' when calling deletePet");
       }
 
 
@@ -147,7 +147,7 @@
 
       // verify the required parameter 'status' is set
       if (status == undefined || status == null) {
-        throw "Missing the required parameter 'status' when calling findPetsByStatus";
+        throw new Error("Missing the required parameter 'status' when calling findPetsByStatus");
       }
 
 
@@ -185,7 +185,7 @@
 
       // verify the required parameter 'tags' is set
       if (tags == undefined || tags == null) {
-        throw "Missing the required parameter 'tags' when calling findPetsByTags";
+        throw new Error("Missing the required parameter 'tags' when calling findPetsByTags");
       }
 
 
@@ -223,7 +223,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling getPetById";
+        throw new Error("Missing the required parameter 'petId' when calling getPetById");
       }
 
 
@@ -261,7 +261,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling updatePet";
+        throw new Error("Missing the required parameter 'body' when calling updatePet");
       }
 
 
@@ -302,7 +302,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling updatePetWithForm";
+        throw new Error("Missing the required parameter 'petId' when calling updatePetWithForm");
       }
 
 
@@ -346,7 +346,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling uploadFile";
+        throw new Error("Missing the required parameter 'petId' when calling uploadFile");
       }
 
 
diff --git a/samples/client/petstore/javascript-promise/src/api/StoreApi.js b/samples/client/petstore/javascript-promise/src/api/StoreApi.js
index b184af1058e..5053b8a708c 100644
--- a/samples/client/petstore/javascript-promise/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/StoreApi.js
@@ -68,7 +68,7 @@
 
       // verify the required parameter 'orderId' is set
       if (orderId == undefined || orderId == null) {
-        throw "Missing the required parameter 'orderId' when calling deleteOrder";
+        throw new Error("Missing the required parameter 'orderId' when calling deleteOrder");
       }
 
 
@@ -137,7 +137,7 @@
 
       // verify the required parameter 'orderId' is set
       if (orderId == undefined || orderId == null) {
-        throw "Missing the required parameter 'orderId' when calling getOrderById";
+        throw new Error("Missing the required parameter 'orderId' when calling getOrderById");
       }
 
 
@@ -175,7 +175,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling placeOrder";
+        throw new Error("Missing the required parameter 'body' when calling placeOrder");
       }
 
 
diff --git a/samples/client/petstore/javascript-promise/src/api/UserApi.js b/samples/client/petstore/javascript-promise/src/api/UserApi.js
index 9186f84e2df..4e66740bd23 100644
--- a/samples/client/petstore/javascript-promise/src/api/UserApi.js
+++ b/samples/client/petstore/javascript-promise/src/api/UserApi.js
@@ -68,7 +68,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUser";
+        throw new Error("Missing the required parameter 'body' when calling createUser");
       }
 
 
@@ -105,7 +105,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUsersWithArrayInput";
+        throw new Error("Missing the required parameter 'body' when calling createUsersWithArrayInput");
       }
 
 
@@ -142,7 +142,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUsersWithListInput";
+        throw new Error("Missing the required parameter 'body' when calling createUsersWithListInput");
       }
 
 
@@ -179,7 +179,7 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling deleteUser";
+        throw new Error("Missing the required parameter 'username' when calling deleteUser");
       }
 
 
@@ -217,7 +217,7 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling getUserByName";
+        throw new Error("Missing the required parameter 'username' when calling getUserByName");
       }
 
 
@@ -256,12 +256,12 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling loginUser";
+        throw new Error("Missing the required parameter 'username' when calling loginUser");
       }
 
       // verify the required parameter 'password' is set
       if (password == undefined || password == null) {
-        throw "Missing the required parameter 'password' when calling loginUser";
+        throw new Error("Missing the required parameter 'password' when calling loginUser");
       }
 
 
@@ -332,12 +332,12 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling updateUser";
+        throw new Error("Missing the required parameter 'username' when calling updateUser");
       }
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling updateUser";
+        throw new Error("Missing the required parameter 'body' when calling updateUser");
       }
 
 
diff --git a/samples/client/petstore/javascript/src/api/FakeApi.js b/samples/client/petstore/javascript/src/api/FakeApi.js
index edda32926dc..04363a01688 100644
--- a/samples/client/petstore/javascript/src/api/FakeApi.js
+++ b/samples/client/petstore/javascript/src/api/FakeApi.js
@@ -75,7 +75,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling testClientModel";
+        throw new Error("Missing the required parameter 'body' when calling testClientModel");
       }
 
 
@@ -134,22 +134,22 @@
 
       // verify the required parameter '_number' is set
       if (_number == undefined || _number == null) {
-        throw "Missing the required parameter '_number' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_number' when calling testEndpointParameters");
       }
 
       // verify the required parameter '_double' is set
       if (_double == undefined || _double == null) {
-        throw "Missing the required parameter '_double' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_double' when calling testEndpointParameters");
       }
 
       // verify the required parameter 'patternWithoutDelimiter' is set
       if (patternWithoutDelimiter == undefined || patternWithoutDelimiter == null) {
-        throw "Missing the required parameter 'patternWithoutDelimiter' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter 'patternWithoutDelimiter' when calling testEndpointParameters");
       }
 
       // verify the required parameter '_byte' is set
       if (_byte == undefined || _byte == null) {
-        throw "Missing the required parameter '_byte' when calling testEndpointParameters";
+        throw new Error("Missing the required parameter '_byte' when calling testEndpointParameters");
       }
 
 
diff --git a/samples/client/petstore/javascript/src/api/PetApi.js b/samples/client/petstore/javascript/src/api/PetApi.js
index aae8c9844d0..158e3d3e84d 100644
--- a/samples/client/petstore/javascript/src/api/PetApi.js
+++ b/samples/client/petstore/javascript/src/api/PetApi.js
@@ -75,7 +75,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling addPet";
+        throw new Error("Missing the required parameter 'body' when calling addPet");
       }
 
 
@@ -122,7 +122,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling deletePet";
+        throw new Error("Missing the required parameter 'petId' when calling deletePet");
       }
 
 
@@ -169,7 +169,7 @@
 
       // verify the required parameter 'status' is set
       if (status == undefined || status == null) {
-        throw "Missing the required parameter 'status' when calling findPetsByStatus";
+        throw new Error("Missing the required parameter 'status' when calling findPetsByStatus");
       }
 
 
@@ -215,7 +215,7 @@
 
       // verify the required parameter 'tags' is set
       if (tags == undefined || tags == null) {
-        throw "Missing the required parameter 'tags' when calling findPetsByTags";
+        throw new Error("Missing the required parameter 'tags' when calling findPetsByTags");
       }
 
 
@@ -261,7 +261,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling getPetById";
+        throw new Error("Missing the required parameter 'petId' when calling getPetById");
       }
 
 
@@ -306,7 +306,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling updatePet";
+        throw new Error("Missing the required parameter 'body' when calling updatePet");
       }
 
 
@@ -354,7 +354,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling updatePetWithForm";
+        throw new Error("Missing the required parameter 'petId' when calling updatePetWithForm");
       }
 
 
@@ -406,7 +406,7 @@
 
       // verify the required parameter 'petId' is set
       if (petId == undefined || petId == null) {
-        throw "Missing the required parameter 'petId' when calling uploadFile";
+        throw new Error("Missing the required parameter 'petId' when calling uploadFile");
       }
 
 
diff --git a/samples/client/petstore/javascript/src/api/StoreApi.js b/samples/client/petstore/javascript/src/api/StoreApi.js
index 5290e1bec0f..98149910aff 100644
--- a/samples/client/petstore/javascript/src/api/StoreApi.js
+++ b/samples/client/petstore/javascript/src/api/StoreApi.js
@@ -75,7 +75,7 @@
 
       // verify the required parameter 'orderId' is set
       if (orderId == undefined || orderId == null) {
-        throw "Missing the required parameter 'orderId' when calling deleteOrder";
+        throw new Error("Missing the required parameter 'orderId' when calling deleteOrder");
       }
 
 
@@ -160,7 +160,7 @@
 
       // verify the required parameter 'orderId' is set
       if (orderId == undefined || orderId == null) {
-        throw "Missing the required parameter 'orderId' when calling getOrderById";
+        throw new Error("Missing the required parameter 'orderId' when calling getOrderById");
       }
 
 
@@ -206,7 +206,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling placeOrder";
+        throw new Error("Missing the required parameter 'body' when calling placeOrder");
       }
 
 
diff --git a/samples/client/petstore/javascript/src/api/UserApi.js b/samples/client/petstore/javascript/src/api/UserApi.js
index b5234f1881b..a63968da0e9 100644
--- a/samples/client/petstore/javascript/src/api/UserApi.js
+++ b/samples/client/petstore/javascript/src/api/UserApi.js
@@ -75,7 +75,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUser";
+        throw new Error("Missing the required parameter 'body' when calling createUser");
       }
 
 
@@ -119,7 +119,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUsersWithArrayInput";
+        throw new Error("Missing the required parameter 'body' when calling createUsersWithArrayInput");
       }
 
 
@@ -163,7 +163,7 @@
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling createUsersWithListInput";
+        throw new Error("Missing the required parameter 'body' when calling createUsersWithListInput");
       }
 
 
@@ -207,7 +207,7 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling deleteUser";
+        throw new Error("Missing the required parameter 'username' when calling deleteUser");
       }
 
 
@@ -253,7 +253,7 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling getUserByName";
+        throw new Error("Missing the required parameter 'username' when calling getUserByName");
       }
 
 
@@ -300,12 +300,12 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling loginUser";
+        throw new Error("Missing the required parameter 'username' when calling loginUser");
       }
 
       // verify the required parameter 'password' is set
       if (password == undefined || password == null) {
-        throw "Missing the required parameter 'password' when calling loginUser";
+        throw new Error("Missing the required parameter 'password' when calling loginUser");
       }
 
 
@@ -390,12 +390,12 @@
 
       // verify the required parameter 'username' is set
       if (username == undefined || username == null) {
-        throw "Missing the required parameter 'username' when calling updateUser";
+        throw new Error("Missing the required parameter 'username' when calling updateUser");
       }
 
       // verify the required parameter 'body' is set
       if (body == undefined || body == null) {
-        throw "Missing the required parameter 'body' when calling updateUser";
+        throw new Error("Missing the required parameter 'body' when calling updateUser");
       }