diff --git a/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenThreeOne/UpdateUserLanguagesToIsoCode.cs b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenThreeOne/UpdateUserLanguagesToIsoCode.cs
new file mode 100644
index 0000000000..50f78ca66d
--- /dev/null
+++ b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenThreeOne/UpdateUserLanguagesToIsoCode.cs
@@ -0,0 +1,38 @@
+using System.Linq;
+using Umbraco.Core.Configuration;
+using Umbraco.Core.Logging;
+using Umbraco.Core.Models.Rdbms;
+using Umbraco.Core.Persistence.SqlSyntax;
+
+namespace Umbraco.Core.Persistence.Migrations.Upgrades.TargetVersionSevenThreeOne
+{
+    /// <summary>
+    /// This fixes the storage of user languages from the old format like en_us to en-US
+    /// </summary>
+    [Migration("7.3.1", 0, GlobalSettings.UmbracoMigrationName)]
+    public class UpdateUserLanguagesToIsoCode : MigrationBase
+    {
+        public UpdateUserLanguagesToIsoCode(ISqlSyntaxProvider sqlSyntax, ILogger logger) : base(sqlSyntax, logger)
+        {
+        }
+
+        public override void Up()
+        {
+            var userData = Context.Database.Fetch<UserDto>(new Sql().Select("*").From<UserDto>(SqlSyntax));
+            foreach (var user in userData.Where(x => x.UserLanguage.Contains("_")))
+            {
+                var languageParts = user.UserLanguage.Split('_');
+                if (languageParts.Length == 2)
+                {
+                    Update.Table("umbracoUser")
+                        .Set(new {userLanguage = languageParts[0] + "-" + languageParts[1].ToUpperInvariant()})
+                        .Where(new {id = user.Id});
+                }
+            }
+        }
+
+        public override void Down()
+        {
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Umbraco.Core/Umbraco.Core.csproj b/src/Umbraco.Core/Umbraco.Core.csproj
index 4552cac7f5..f9e3f3b38f 100644
--- a/src/Umbraco.Core/Umbraco.Core.csproj
+++ b/src/Umbraco.Core/Umbraco.Core.csproj
@@ -435,6 +435,7 @@
     <Compile Include="Media\Exif\TIFFHeader.cs" />
     <Compile Include="Media\Exif\TIFFStrip.cs" />
     <Compile Include="Media\Exif\Utility.cs" />
+    <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenThreeOne\UpdateUserLanguagesToIsoCode.cs" />
     <Compile Include="Persistence\RecordPersistenceType.cs" />
     <Compile Include="Persistence\Relators\AccessRulesRelator.cs" />
     <Compile Include="Persistence\Repositories\AuditRepository.cs" />
diff --git a/src/Umbraco.Web/Editors/MediaController.cs b/src/Umbraco.Web/Editors/MediaController.cs
index e03f55a785..65ba7a5cca 100644
--- a/src/Umbraco.Web/Editors/MediaController.cs
+++ b/src/Umbraco.Web/Editors/MediaController.cs
@@ -471,7 +471,7 @@ namespace Umbraco.Web.Editors
                 {
                     tempFiles.Notifications.Add(new Notification(
                         Services.TextService.Localize("speechBubbles/operationFailedHeader"),
-                        "Cannot upload file " + file + ", it is not an approved file type",
+                        "Cannot upload file " + file.Headers.ContentDisposition.FileName + ", it is not an approved file type",
                         SpeechBubbleIcon.Warning));
                 }
             }
diff --git a/src/Umbraco.Web/umbraco.presentation/umbraco/users/EditUser.aspx.cs b/src/Umbraco.Web/umbraco.presentation/umbraco/users/EditUser.aspx.cs
index 28991f1f6b..d9605506b4 100644
--- a/src/Umbraco.Web/umbraco.presentation/umbraco/users/EditUser.aspx.cs
+++ b/src/Umbraco.Web/umbraco.presentation/umbraco/users/EditUser.aspx.cs
@@ -19,7 +19,6 @@ using umbraco.BasePages;
 using umbraco.BusinessLogic;
 using umbraco.businesslogic.Exceptions;
 using umbraco.cms.businesslogic.media;
-using umbraco.cms.businesslogic.propertytype;
 using umbraco.cms.businesslogic.web;
 using umbraco.controls;
 using umbraco.presentation.channels.businesslogic;
@@ -28,7 +27,9 @@ using umbraco.providers;
 using umbraco.cms.presentation.Trees;
 using Umbraco.Core.IO;
 using Umbraco.Core;
+using Umbraco.Core.Models;
 using Umbraco.Core.Services;
+using PropertyType = umbraco.cms.businesslogic.propertytype.PropertyType;
 
 namespace umbraco.cms.presentation.user
 {
@@ -106,8 +107,8 @@ namespace umbraco.cms.presentation.user
                     userType.Items.Add(li);
                 }
             }
-
-            var userCulture = Services.TextService.ConvertToSupportedCultureWithRegionCode(new CultureInfo(u.Language));
+            
+            var userCulture = UserExtensions.GetUserCulture(u.Language, Services.TextService);
 
             // Populate ui language lsit
             foreach (var lang in Services.TextService.GetSupportedCultures())
diff --git a/src/Umbraco.Web/umbraco.presentation/umbraco/webservices/MediaUploader.ashx.cs b/src/Umbraco.Web/umbraco.presentation/umbraco/webservices/MediaUploader.ashx.cs
index 1a8b6f0313..54ab4aa12d 100644
--- a/src/Umbraco.Web/umbraco.presentation/umbraco/webservices/MediaUploader.ashx.cs
+++ b/src/Umbraco.Web/umbraco.presentation/umbraco/webservices/MediaUploader.ashx.cs
@@ -161,7 +161,7 @@ namespace umbraco.presentation.umbraco.webservices
                         var ext = uploadFile.FileName.Substring(uploadFile.FileName.LastIndexOf('.') + 1).ToLower();
                         if (UmbracoConfig.For.UmbracoSettings().Content.DisallowedUploadFiles.Contains(ext))
                         {
-                            LogHelper.Warn<MediaUploader>("Cannot upload file " + uploadFile + ", it is not an approved file type");
+                            LogHelper.Warn<MediaUploader>("Cannot upload file " + uploadFile.FileName + ", it is not approved in `disallowedUploadFiles` in ~/config/UmbracoSettings.config");
                             continue;
                         }