diff --git a/src/Umbraco.Core/Configuration/ConfigConnectionString.cs b/src/Umbraco.Core/Configuration/ConfigConnectionString.cs
index 18bdace632..116b96df9c 100644
--- a/src/Umbraco.Core/Configuration/ConfigConnectionString.cs
+++ b/src/Umbraco.Core/Configuration/ConfigConnectionString.cs
@@ -22,7 +22,7 @@ namespace Umbraco.Cms.Core.Configuration
         {
             if (string.IsNullOrEmpty(connectionString))
             {
-                return null;
+                return connectionString;
             }
 
             var builder = new DbConnectionStringBuilder
@@ -41,6 +41,9 @@ namespace Umbraco.Cms.Core.Configuration
                 if (!string.IsNullOrEmpty(dataDirectory))
                 {
                     builder[attachDbFileNameKey] = attachDbFileName.Replace(dataDirectoryPlaceholder, dataDirectory);
+
+                    // Mutate the existing connection string (note: the builder also lowercases the properties)
+                    connectionString = builder.ToString();
                 }
             }
 
@@ -50,7 +53,7 @@ namespace Umbraco.Cms.Core.Configuration
                 providerName = ParseProviderName(builder);
             }
 
-            return builder.ToString();
+            return connectionString;
         }
 
         /// <summary>
diff --git a/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs b/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
index f9e36d8d12..55fdd24f77 100644
--- a/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
@@ -4,7 +4,6 @@ using Microsoft.Extensions.Options;
 using Umbraco.Cms.Core;
 using Umbraco.Cms.Core.Configuration;
 using Umbraco.Cms.Core.Configuration.Models;
-using Umbraco.Cms.Core.Hosting;
 using Umbraco.Cms.Core.Migrations;
 using Umbraco.Cms.Core.Scoping;
 using Umbraco.Cms.Core.Services;
@@ -144,7 +143,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
 
         #region Configure Connection String
 
-        public const string EmbeddedDatabaseConnectionString = @"Data Source=|DataDirectory|\Umbraco.sdf;Flush Interval=1;";
+        public const string EmbeddedDatabaseConnectionString = @"Data Source=|DataDirectory|\Umbraco.sdf;Flush Interval=1";
 
         /// <summary>
         /// Configures a connection string for the embedded database.