diff --git a/Chagelog.md b/Chagelog.md
index 28073b6..d223121 100644
--- a/Chagelog.md
+++ b/Chagelog.md
@@ -1,2 +1,6 @@
+### 9/12/2017 - 1.9.4
+- For `"collectionFormat": "multi"` in `query` parameters, if the item type is null or undefined then we treat it as an empty string
+- Removing the check that primaryType in the formatted reference value should only be a string. It can be any other primary type apart from "string".
+ 
 ### 9/5/2017 - 1.9.3
 - Added support for `"collectionFormat": "multi"` in `query` parameters https://github.com/Azure/autorest/issues/717.
\ No newline at end of file
diff --git a/package.json b/package.json
index a06f1be..e8ceed9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@microsoft.azure/autorest.nodejs",
-  "version": "1.9.3",
+  "version": "1.9.4",
   "description": "The NodeJS extension for classic generators in AutoRest.",
   "scripts": {
     "start": "dotnet src/bin/netcoreapp2.0/autorest.nodejs.dll --server",
diff --git a/src/vanilla/ClientModelExtensions.cs b/src/vanilla/ClientModelExtensions.cs
index da39474..c207d23 100644
--- a/src/vanilla/ClientModelExtensions.cs
+++ b/src/vanilla/ClientModelExtensions.cs
@@ -28,7 +28,7 @@ public static string GetHttpMethod(this HttpMethod method)
         }
 
         /// <summary>
-        /// Format the value of a sequence given the modeled element format.  Note that only sequences of strings are supported
+        /// Format the value of a sequence given the modeled element format.
         /// </summary>
         /// <param name="parameter">The parameter to format</param>
         /// <returns>A reference to the formatted parameter value</returns>
@@ -52,12 +52,6 @@ public static string GetFormattedReferenceValue(this Parameter parameter)
                 primaryType = New<PrimaryType>(KnownPrimaryType.String);
             }
 
-            if (primaryType == null || primaryType.KnownPrimaryType != KnownPrimaryType.String)
-            {
-                throw new InvalidOperationException(
-                    $"Cannot generate a formatted sequence from a non-string array parameter {parameter}");
-            }
-
             return $"{parameter.Name}.join('{parameter.CollectionFormat.GetSeparator()}')";
         }
 
diff --git a/src/vanilla/Model/MethodJs.cs b/src/vanilla/Model/MethodJs.cs
index 648bb31..cd388d8 100644
--- a/src/vanilla/Model/MethodJs.cs
+++ b/src/vanilla/Model/MethodJs.cs
@@ -666,6 +666,7 @@ protected virtual void BuildQueryParameterArray(IndentedStringBuilder builder)
                            .AppendLine(queryAddFormat, queryParameter.SerializedName, "''").Outdent()
                            .AppendLine("} else {").Indent()
                            .AppendLine("for (let item of {0}) {{", queryParameter.Name).Indent()
+                           .AppendLine("item = (item === null || item === undefined) ? '' : item;")
                            .AppendLine(queryAddFormat, queryParameter.SerializedName, "'' + item").Outdent()
                            .AppendLine("}").Outdent()
                            .AppendLine("}").Outdent();
diff --git a/test/azure/Expected/AcceptanceTests/CustomBaseUri/operations/paths.js b/test/azure/Expected/AcceptanceTests/CustomBaseUri/operations/paths.js
index 0a959b5..78f8f06 100644
--- a/test/azure/Expected/AcceptanceTests/CustomBaseUri/operations/paths.js
+++ b/test/azure/Expected/AcceptanceTests/CustomBaseUri/operations/paths.js
@@ -48,15 +48,15 @@ function _getEmpty(accountName, options, callback) {
   }
   // Validate
   try {
-    if (this.client.acceptLanguage !== null && this.client.acceptLanguage !== undefined && typeof this.client.acceptLanguage.valueOf() !== 'string') {
-      throw new Error('this.client.acceptLanguage must be of type string.');
-    }
     if (accountName === null || accountName === undefined || typeof accountName.valueOf() !== 'string') {
       throw new Error('accountName cannot be null or undefined and it must be of type string.');
     }
     if (this.client.host === null || this.client.host === undefined || typeof this.client.host.valueOf() !== 'string') {
       throw new Error('this.client.host cannot be null or undefined and it must be of type string.');
     }
+    if (this.client.acceptLanguage !== null && this.client.acceptLanguage !== undefined && typeof this.client.acceptLanguage.valueOf() !== 'string') {
+      throw new Error('this.client.acceptLanguage must be of type string.');
+    }
   } catch (error) {
     return callback(error);
   }
diff --git a/test/vanilla/AcceptanceTests/acceptanceTests.js b/test/vanilla/AcceptanceTests/acceptanceTests.js
index afefe1d..b7a2050 100644
--- a/test/vanilla/AcceptanceTests/acceptanceTests.js
+++ b/test/vanilla/AcceptanceTests/acceptanceTests.js
@@ -2433,7 +2433,7 @@ describe('nodejs', function () {
         });
         describe('Url MultiFormatCollection Client', function () {
             var testClient = new urlMultiCollectionClient(baseUri, clientOptions);
-            it('should work when query parameter with collection format multi is an empty array', function (done) {
+            it('should work when query parameter with collection format multi is null', function (done) {
                 testClient.queries.arrayStringMultiNull(function (err, result, request, response) {
                     should.not.exist(err);
                     done();
diff --git a/test/vanilla/AcceptanceTests/acceptanceTests.ts b/test/vanilla/AcceptanceTests/acceptanceTests.ts
index 5258430..2d9ef66 100644
--- a/test/vanilla/AcceptanceTests/acceptanceTests.ts
+++ b/test/vanilla/AcceptanceTests/acceptanceTests.ts
@@ -2611,7 +2611,7 @@ describe('nodejs', function () {
 
     describe('Url MultiFormatCollection Client', function () {
       var testClient = new urlMultiCollectionClient(baseUri, clientOptions);
-      it('should work when query parameter with collection format multi is an empty array', function (done) {
+      it('should work when query parameter with collection format multi is null', function (done) {
         testClient.queries.arrayStringMultiNull((err, result, request, response) => {
           should.not.exist(err);
           done();
diff --git a/test/vanilla/Expected/AcceptanceTests/UrlMultiCollectionFormat/operations/queries.js b/test/vanilla/Expected/AcceptanceTests/UrlMultiCollectionFormat/operations/queries.js
index 5142d56..ee57c68 100644
--- a/test/vanilla/Expected/AcceptanceTests/UrlMultiCollectionFormat/operations/queries.js
+++ b/test/vanilla/Expected/AcceptanceTests/UrlMultiCollectionFormat/operations/queries.js
@@ -69,6 +69,7 @@ function _arrayStringMultiNull(options, callback) {
       queryParameters.push('arrayQuery=' + encodeURIComponent(''));
     } else {
       for (let item of arrayQuery) {
+        item = (item === null || item === undefined) ? '' : item;
         queryParameters.push('arrayQuery=' + encodeURIComponent('' + item));
       }
     }
@@ -188,6 +189,7 @@ function _arrayStringMultiEmpty(options, callback) {
       queryParameters.push('arrayQuery=' + encodeURIComponent(''));
     } else {
       for (let item of arrayQuery) {
+        item = (item === null || item === undefined) ? '' : item;
         queryParameters.push('arrayQuery=' + encodeURIComponent('' + item));
       }
     }
@@ -308,6 +310,7 @@ function _arrayStringMultiValid(options, callback) {
       queryParameters.push('arrayQuery=' + encodeURIComponent(''));
     } else {
       for (let item of arrayQuery) {
+        item = (item === null || item === undefined) ? '' : item;
         queryParameters.push('arrayQuery=' + encodeURIComponent('' + item));
       }
     }