diff --git a/.gitignore b/.gitignore
index 21ad03fd2577..3f0661881fe4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,6 +46,7 @@ cmake/
 # Test results
 **/*.trx
 /TestResults
+**/TestResults
 /test/dotnet.Tests/CompletionTests/snapshots/**/**.received.*
 
 # Live Unit Testing
diff --git a/template_feed/Microsoft.DotNet.Common.ItemTemplates/content/Solution/.template.config/template.json b/template_feed/Microsoft.DotNet.Common.ItemTemplates/content/Solution/.template.config/template.json
index a4e584a02541..d6f4dca9c976 100644
--- a/template_feed/Microsoft.DotNet.Common.ItemTemplates/content/Solution/.template.config/template.json
+++ b/template_feed/Microsoft.DotNet.Common.ItemTemplates/content/Solution/.template.config/template.json
@@ -20,7 +20,7 @@
       "type": "parameter",
       "displayName": "Solution file format",
       "description": "Choose the format for the solution file: sln or slnx.",
-      "defaultValue": "sln",
+      "defaultValue": "slnx",
       "datatype": "choice",
       "choices": [
         {
diff --git a/test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibrary.cs b/test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibrary.cs
index a7a460ab70cc..ee23eef9dec6 100644
--- a/test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibrary.cs
+++ b/test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibrary.cs
@@ -686,7 +686,7 @@ private void TestInvalidTargetFramework(string testName, string targetFramework,
                 new DotnetNewCommand(Log)
                     .WithVirtualHive()
                     .WithWorkingDirectory(testAsset.TestRoot)
-                    .Execute("sln")
+                    .Execute("sln", "--format", "sln")
                     .Should()
                     .Pass();
 
diff --git a/test/Microsoft.NET.TestFramework/TestAssetsManager.cs b/test/Microsoft.NET.TestFramework/TestAssetsManager.cs
index 3f397d133a81..479a6b57254e 100644
--- a/test/Microsoft.NET.TestFramework/TestAssetsManager.cs
+++ b/test/Microsoft.NET.TestFramework/TestAssetsManager.cs
@@ -95,7 +95,7 @@ public TestAsset CreateTestProjects(
 
             var testAsset = CreateTestProjectsInDirectory(testProjects, testDestinationDirectory);
 
-            var slnCreationResult = new DotnetNewCommand(Log, "sln")
+            var slnCreationResult = new DotnetNewCommand(Log, "sln", "--format", "sln")
                 .WithVirtualHive()
                 .WithWorkingDirectory(testDestinationDirectory)
                 .Execute();
diff --git a/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item.verified/Solution-File/item.sln b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#sln.verified/Solution-File/item.sln
similarity index 100%
rename from test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item.verified/Solution-File/item.sln
rename to test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#sln.verified/Solution-File/item.sln
diff --git a/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#sln.verified/std-streams/stdout.txt b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#sln.verified/std-streams/stdout.txt
new file mode 100644
index 000000000000..70cab17a4b13
--- /dev/null
+++ b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#sln.verified/std-streams/stdout.txt
@@ -0,0 +1 @@
+The template "%TEMPLATE_NAME%" was created successfully.
\ No newline at end of file
diff --git a/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/Solution-File/item.slnx b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/Solution-File/item.slnx
new file mode 100644
index 000000000000..ba788ff0d17d
--- /dev/null
+++ b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/Solution-File/item.slnx
@@ -0,0 +1,2 @@
+<Solution>
+</Solution>
diff --git a/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/std-streams/stdout.txt b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/std-streams/stdout.txt
new file mode 100644
index 000000000000..70cab17a4b13
--- /dev/null
+++ b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item#--format#slnx.verified/std-streams/stdout.txt
@@ -0,0 +1 @@
+The template "%TEMPLATE_NAME%" was created successfully.
\ No newline at end of file
diff --git a/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item.verified/Solution-File/item.slnx b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item.verified/Solution-File/item.slnx
new file mode 100644
index 000000000000..ba788ff0d17d
--- /dev/null
+++ b/test/dotnet-new.IntegrationTests/Approvals/AllCommonItemsCreate.-o#Solution-File#-n#item.verified/Solution-File/item.slnx
@@ -0,0 +1,2 @@
+<Solution>
+</Solution>
diff --git a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Linux.verified.txt b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Linux.verified.txt
index 2e38e42367e5..799ac7d3a9dc 100644
--- a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Linux.verified.txt
+++ b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Linux.verified.txt
@@ -3,7 +3,7 @@
 Processing post-creation actions...
 Adding
     project(s): %working directory%/MyProject.csproj
-    to solution file: %working directory%/MySolution.sln
+    to solution file: %working directory%/MySolution.slnx
     solution folder: src
 %CALLBACK OUTPUT%
 Successfully added project(s) to a solution file.
\ No newline at end of file
diff --git a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.OSX.verified.txt b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.OSX.verified.txt
index 2e38e42367e5..799ac7d3a9dc 100644
--- a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.OSX.verified.txt
+++ b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.OSX.verified.txt
@@ -3,7 +3,7 @@
 Processing post-creation actions...
 Adding
     project(s): %working directory%/MyProject.csproj
-    to solution file: %working directory%/MySolution.sln
+    to solution file: %working directory%/MySolution.slnx
     solution folder: src
 %CALLBACK OUTPUT%
 Successfully added project(s) to a solution file.
\ No newline at end of file
diff --git a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Windows.verified.txt b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Windows.verified.txt
index e6b887af4bf2..951a5359e54d 100644
--- a/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Windows.verified.txt
+++ b/test/dotnet-new.IntegrationTests/Approvals/PostActionTests.AddProjectToSolution_Basic_Approval.Windows.verified.txt
@@ -3,7 +3,7 @@
 Processing post-creation actions...
 Adding
     project(s): %working directory%\MyProject.csproj
-    to solution file: %working directory%\MySolution.sln
+    to solution file: %working directory%\MySolution.slnx
     solution folder: src
 %CALLBACK OUTPUT%
 Successfully added project(s) to a solution file.
\ No newline at end of file
diff --git a/test/dotnet-new.IntegrationTests/CommonTemplatesTests.cs b/test/dotnet-new.IntegrationTests/CommonTemplatesTests.cs
index ad1499294f64..3a373345ff59 100644
--- a/test/dotnet-new.IntegrationTests/CommonTemplatesTests.cs
+++ b/test/dotnet-new.IntegrationTests/CommonTemplatesTests.cs
@@ -37,6 +37,8 @@ public CommonTemplatesTests(SharedHomeDirectory fixture, ITestOutputHelper log)
         [InlineData("dotnet gitignore file", "gitignore", null)]
         [InlineData("dotnet gitignore file", ".gitignore", null)]
         [InlineData("Solution File", "sln", null)]
+        [InlineData("Solution File", "sln", new[] { "--format", "sln" })]
+        [InlineData("Solution File", "sln", new[] { "--format", "slnx" })]
         [InlineData("Solution File", "solution", null)]
         [InlineData("Dotnet local tool manifest file", "tool-manifest", null)]
         [InlineData("Web Config", "webconfig", null)]
diff --git a/test/dotnet-new.IntegrationTests/PostActionTests.cs b/test/dotnet-new.IntegrationTests/PostActionTests.cs
index 5067e8bba7dd..3e9c6a391914 100644
--- a/test/dotnet-new.IntegrationTests/PostActionTests.cs
+++ b/test/dotnet-new.IntegrationTests/PostActionTests.cs
@@ -775,7 +775,7 @@ public void AddProjectToSolution_Basic(string templatePartLocation, string templ
                 .And.HaveStdOutContaining("solution folder: src")
                 .And.NotHaveStdOutContaining("Manual instructions: Add the generated files to solution manually.");
 
-            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(workingDirectory, "MySolution.sln")));
+            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(workingDirectory, "MySolution.slnx")));
         }
 
         [Fact]
@@ -811,7 +811,7 @@ public void AddProjectToSolution_BasicInSolutionRoot()
                 .And.HaveStdOutContaining(Path.Combine(outputDirectory, "MySolution.sln"))
                 .And.HaveStdOutContaining(Path.Combine(outputDirectory, "MyProject.csproj"));
 
-            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(outputDirectory, "MySolution.sln")));
+            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(outputDirectory, "MySolution.slnx")));
         }
 
         [Fact]
@@ -847,7 +847,7 @@ public void AddProjectToSolution_WithOutputAbsolutePath()
                 .And.HaveStdOutContaining(Path.Combine(outputDirectory, "MySolution.sln"))
                 .And.HaveStdOutContaining(Path.Combine(outputDirectory, "MyProject.csproj"));
 
-            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(outputDirectory, "MySolution.sln")));
+            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(outputDirectory, "MySolution.slnx")));
         }
 
         [Fact]
@@ -883,7 +883,7 @@ public void AddProjectToSolution_WithOutputRelativePath()
                 .And.HaveStdOutContaining(Path.Combine(workingDirectory, outputDirectory, "MySolution.sln"))
                 .And.HaveStdOutContaining(Path.Combine(workingDirectory, outputDirectory, "MyProject.csproj"));
 
-            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(workingDirectory, outputDirectory, "MySolution.sln")));
+            Assert.Contains("MyProject.csproj", File.ReadAllText(Path.Combine(workingDirectory, outputDirectory, "MySolution.slnx")));
         }
 
         [Fact]
@@ -916,11 +916,11 @@ public void AddProjectToSolution_PrimaryOutputIndexes()
                 .And.HaveStdOutContaining("solution folder: Server")
                 .And.NotHaveStdOutContaining("Manual instructions: Add generated Server project to solution manually to folder 'Server'.");
 
-            Assert.True(File.Exists(Path.Combine(workingDirectory, "MySolution.sln")));
+            Assert.True(File.Exists(Path.Combine(workingDirectory, "MySolution.slnx")));
             Assert.True(File.Exists(Path.Combine(workingDirectory, "Server/Server.csproj")));
             Assert.True(File.Exists(Path.Combine(workingDirectory, "Client/Client.csproj")));
 
-            string solutionFileContents = File.ReadAllText(Path.Combine(workingDirectory, "MySolution.sln"));
+            string solutionFileContents = File.ReadAllText(Path.Combine(workingDirectory, "MySolution.slnx"));
             Assert.Contains("Server.csproj", solutionFileContents);
             Assert.DoesNotContain("Client.csproj", solutionFileContents);
         }