diff --git a/src/Umbraco.Core/Configuration/UmbracoSettings/ContentElement.cs b/src/Umbraco.Core/Configuration/UmbracoSettings/ContentElement.cs
index 3ebb632882..7c6ff4405f 100644
--- a/src/Umbraco.Core/Configuration/UmbracoSettings/ContentElement.cs
+++ b/src/Umbraco.Core/Configuration/UmbracoSettings/ContentElement.cs
@@ -29,11 +29,11 @@ namespace Umbraco.Core.Configuration.UmbracoSettings
         internal InnerTextConfigurationElement<MacroErrorBehaviour> MacroErrors => GetOptionalTextElement("MacroErrors", MacroErrorBehaviour.Inline);
 
         [ConfigurationProperty("disallowedUploadFiles")]
-        internal CommaDelimitedConfigurationElement DisallowedUploadFiles => GetOptionalDelimitedElement("disallowedUploadFiles", new[] {"ashx", "aspx", "ascx", "config", "cshtml", "vbhtml", "asmx", "air", "axd"});
+        internal CommaDelimitedConfigurationElement DisallowedUploadFiles => GetOptionalDelimitedElement("disallowedUploadFiles", new[] {"ashx", "aspx", "ascx", "config", "cshtml", "vbhtml", "asmx", "air", "axd", "xamlx"});
 
         [ConfigurationProperty("allowedUploadFiles")]
         internal CommaDelimitedConfigurationElement AllowedUploadFiles => GetOptionalDelimitedElement("allowedUploadFiles", new string[0]);
-        
+
         [ConfigurationProperty("showDeprecatedPropertyEditors")]
         internal InnerTextConfigurationElement<bool> ShowDeprecatedPropertyEditors => GetOptionalTextElement("showDeprecatedPropertyEditors", false);
 
diff --git a/src/Umbraco.Tests/Configurations/UmbracoSettings/ContentElementTests.cs b/src/Umbraco.Tests/Configurations/UmbracoSettings/ContentElementTests.cs
index 33df3caaad..498c12101c 100644
--- a/src/Umbraco.Tests/Configurations/UmbracoSettings/ContentElementTests.cs
+++ b/src/Umbraco.Tests/Configurations/UmbracoSettings/ContentElementTests.cs
@@ -83,7 +83,7 @@ namespace Umbraco.Tests.Configurations.UmbracoSettings
         [Test]
         public void DisallowedUploadFiles()
         {
-            Assert.IsTrue(SettingsSection.Content.DisallowedUploadFiles.All(x => "ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd".Split(',').Contains(x)));
+            Assert.IsTrue(SettingsSection.Content.DisallowedUploadFiles.All(x => "ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd,xamlx".Split(',').Contains(x)));
         }
 
         [Test]
diff --git a/src/Umbraco.Tests/Configurations/UmbracoSettings/umbracoSettings.config b/src/Umbraco.Tests/Configurations/UmbracoSettings/umbracoSettings.config
index 8cbb799d88..d802cfc7ad 100644
--- a/src/Umbraco.Tests/Configurations/UmbracoSettings/umbracoSettings.config
+++ b/src/Umbraco.Tests/Configurations/UmbracoSettings/umbracoSettings.config
@@ -18,9 +18,9 @@
           <lengthFieldAlias>umbracoBytes2</lengthFieldAlias>
           <extensionFieldAlias>umbracoExtension2</extensionFieldAlias>
         </uploadField>
-      </autoFillImageProperties>      
+      </autoFillImageProperties>
     </imaging>
-   
+
     <errors>
       <!-- the id of the page that should be shown if the page is not found -->
       <!--<error404>
@@ -50,12 +50,12 @@
                         error handler is defined then you'll see the Yellow Screen Of Death (YSOD) error page.
              Note the error can also be handled by the umbraco.macro.Error event, where you can log/alarm with your own code and change the behaviour per event. -->
     <MacroErrors>inline</MacroErrors>
-    
+
     <!-- These file types will not be allowed to be uploaded via the upload control for media and content -->
-    <disallowedUploadFiles>ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd</disallowedUploadFiles>
+    <disallowedUploadFiles>ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd,xamlx</disallowedUploadFiles>
 
     <!-- If completed, only the file extensions listed below will be allowed to be uploaded.  If empty, disallowedUploadFiles will apply to prevent upload of specific file extensions. -->
-    <allowedUploadFiles>jpg,png,gif</allowedUploadFiles>    
+    <allowedUploadFiles>jpg,png,gif</allowedUploadFiles>
 
   </content>
 
@@ -108,7 +108,7 @@
     <maxLogAge>1440</maxLogAge>
   </logging>
 
-  <!-- 
+  <!--
     web.routing
       @trySkipIisCustomErrors
         Tries to skip IIS custom errors.
diff --git a/src/Umbraco.Web.UI/config/umbracoSettings.Release.config b/src/Umbraco.Web.UI/config/umbracoSettings.Release.config
index c20ef3038b..5ce2c24d41 100644
--- a/src/Umbraco.Web.UI/config/umbracoSettings.Release.config
+++ b/src/Umbraco.Web.UI/config/umbracoSettings.Release.config
@@ -183,7 +183,7 @@
     <MacroErrors>throw</MacroErrors>
 
     <!-- These file types will not be allowed to be uploaded via the upload control for media and content -->
-    <disallowedUploadFiles>ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd,swf,xml,xhtml,html,htm,php,htaccess</disallowedUploadFiles>
+    <disallowedUploadFiles>ashx,aspx,ascx,config,cshtml,vbhtml,asmx,air,axd,swf,xml,xhtml,html,htm,php,htaccess,xamlx</disallowedUploadFiles>
 
     <!-- You can specify your own background image for the login screen here. This path is relative to the ~/umbraco path. The default location is: /umbraco/assets/img/login.jpg -->
     <loginBackgroundImage>assets/img/login.jpg</loginBackgroundImage>