diff --git a/src/Cli/dotnet/commands/dotnet-new/PostActions/DotnetSlnPostActionProcessor.cs b/src/Cli/dotnet/commands/dotnet-new/PostActions/DotnetSlnPostActionProcessor.cs
index 28143fd21d82..c03937f3723e 100644
--- a/src/Cli/dotnet/commands/dotnet-new/PostActions/DotnetSlnPostActionProcessor.cs
+++ b/src/Cli/dotnet/commands/dotnet-new/PostActions/DotnetSlnPostActionProcessor.cs
@@ -27,8 +27,11 @@ public DotnetSlnPostActionProcessor(Func<string, IReadOnlyList<string>, string?,
 
         internal static IReadOnlyList<string> FindSolutionFilesAtOrAbovePath(IPhysicalFileSystem fileSystem, string outputBasePath)
         {
-            return FileFindHelpers.FindFilesAtOrAbovePath(fileSystem, outputBasePath, "*.sln")
-                ?? FileFindHelpers.FindFilesAtOrAbovePath(fileSystem, outputBasePath, "*.slnx");
+            return
+            [
+                ..FileFindHelpers.FindFilesAtOrAbovePath(fileSystem, outputBasePath, "*.sln"),
+                ..FileFindHelpers.FindFilesAtOrAbovePath(fileSystem, outputBasePath, "*.slnx")
+            ];
         }
 
         // The project files to add are a subset of the primary outputs, specifically the primary outputs indicated by the primaryOutputIndexes post action argument (semicolon separated)
diff --git a/test/dotnet.Tests/dotnet-new/DotnetSlnPostActionTests.cs b/test/dotnet.Tests/dotnet-new/DotnetSlnPostActionTests.cs
index f32e970ff806..3dc919c05eb2 100644
--- a/test/dotnet.Tests/dotnet-new/DotnetSlnPostActionTests.cs
+++ b/test/dotnet.Tests/dotnet-new/DotnetSlnPostActionTests.cs
@@ -19,11 +19,13 @@ public DotnetSlnPostActionTests(EnvironmentSettingsHelper environmentSettingsHel
             _engineEnvironmentSettings = environmentSettingsHelper.CreateEnvironment(hostIdentifier: GetType().Name, virtualize: true);
         }
 
-        [Fact(DisplayName = nameof(AddProjectToSolutionPostActionFindSolutionFileAtOutputPath))]
-        public void AddProjectToSolutionPostActionFindSolutionFileAtOutputPath()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionPostActionFindSolutionFileAtOutputPath(string solutionFileName)
         {
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string solutionFileFullPath = Path.Combine(targetBasePath, "MySln.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string solutionFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(solutionFileFullPath, string.Empty);
 
             IReadOnlyList<string> solutionFiles = DotnetSlnPostActionProcessor.FindSolutionFilesAtOrAbovePath(_engineEnvironmentSettings.Host.FileSystem, targetBasePath);
@@ -34,7 +36,7 @@ public void AddProjectToSolutionPostActionFindSolutionFileAtOutputPath()
         [Fact(DisplayName = nameof(AddProjectToSolutionPostActionFindsOneProjectToAdd))]
         public void AddProjectToSolutionPostActionFindsOneProjectToAdd()
         {
-            string outputBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
+            string outputBasePath = GetVirtualizedRootPath();
             IPostAction postAction = new MockPostAction(default, default, default, default, default!)
             {
                 ActionId = DotnetSlnPostActionProcessor.ActionProcessorId,
@@ -160,14 +162,16 @@ public void AddProjectToSolutionPostActionWithoutPrimaryOutputIndexesWithOutputB
             Assert.Contains(outputFileFullPath1, foundProjectFiles.ToList());
         }
 
-        [Fact(DisplayName = nameof(AddProjectToSolutionCanTargetASingleProjectWithAJsonArray))]
-        public void AddProjectToSolutionCanTargetASingleProjectWithAJsonArray()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionCanTargetASingleProjectWithAJsonArray(string solutionFileName)
         {
             var callback = new MockAddProjectToSolutionCallback();
             var actionProcessor = new DotnetSlnPostActionProcessor(callback.AddProjectToSolution);
 
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string slnFileFullPath = Path.Combine(targetBasePath, "MyApp.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string slnFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             string projFileFullPath = Path.Combine(targetBasePath, "MyApp.csproj");
 
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(slnFileFullPath, "");
@@ -189,14 +193,16 @@ public void AddProjectToSolutionCanTargetASingleProjectWithAJsonArray()
             Assert.Equal(slnFileFullPath, callback.Solution);
         }
 
-        [Fact(DisplayName = nameof(AddProjectToSolutionCanTargetASingleProjectWithTheProjectName))]
-        public void AddProjectToSolutionCanTargetASingleProjectWithTheProjectName()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionCanTargetASingleProjectWithTheProjectName(string solutionFileName)
         {
             var callback = new MockAddProjectToSolutionCallback();
             var actionProcessor = new DotnetSlnPostActionProcessor(callback.AddProjectToSolution);
 
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string slnFileFullPath = Path.Combine(targetBasePath, "MyApp.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string slnFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             string projFileFullPath = Path.Combine(targetBasePath, "MyApp.csproj");
 
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(slnFileFullPath, "");
@@ -218,14 +224,16 @@ public void AddProjectToSolutionCanTargetASingleProjectWithTheProjectName()
             Assert.Equal(slnFileFullPath, callback.Solution);
         }
 
-        [Fact(DisplayName = nameof(AddProjectToSolutionCanPlaceProjectInSolutionRoot))]
-        public void AddProjectToSolutionCanPlaceProjectInSolutionRoot()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionCanPlaceProjectInSolutionRoot(string solutionFileName)
         {
             var callback = new MockAddProjectToSolutionCallback();
             var actionProcessor = new DotnetSlnPostActionProcessor(callback.AddProjectToSolution);
 
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string slnFileFullPath = Path.Combine(targetBasePath, "MyApp.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string slnFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             string projFileFullPath = Path.Combine(targetBasePath, "MyApp.csproj");
 
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(slnFileFullPath, "");
@@ -250,14 +258,16 @@ public void AddProjectToSolutionCanPlaceProjectInSolutionRoot()
             Assert.Null(callback.TargetFolder);
         }
 
-        [Fact]
-        public void AddProjectToSolutionCanPlaceProjectInSolutionFolder()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionCanPlaceProjectInSolutionFolder(string solutionFileName)
         {
             var callback = new MockAddProjectToSolutionCallback();
             var actionProcessor = new DotnetSlnPostActionProcessor(callback.AddProjectToSolution);
 
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string slnFileFullPath = Path.Combine(targetBasePath, "MyApp.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string slnFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             string projFileFullPath = Path.Combine(targetBasePath, "MyApp.csproj");
 
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(slnFileFullPath, "");
@@ -282,14 +292,16 @@ public void AddProjectToSolutionCanPlaceProjectInSolutionFolder()
             Assert.Equal("src", callback.TargetFolder);
         }
 
-        [Fact]
-        public void AddProjectToSolutionFailsWhenSolutionFolderAndInRootSpecified()
+        [Theory]
+        [InlineData("MySln.sln")]
+        [InlineData("MySln.slnx")]
+        public void AddProjectToSolutionFailsWhenSolutionFolderAndInRootSpecified(string solutionFileName)
         {
             var callback = new MockAddProjectToSolutionCallback();
             var actionProcessor = new DotnetSlnPostActionProcessor(callback.AddProjectToSolution);
 
-            string targetBasePath = _engineEnvironmentSettings.GetTempVirtualizedPath();
-            string slnFileFullPath = Path.Combine(targetBasePath, "MyApp.sln");
+            string targetBasePath = GetVirtualizedRootPath();
+            string slnFileFullPath = Path.Combine(targetBasePath, solutionFileName);
             string projFileFullPath = Path.Combine(targetBasePath, "MyApp.csproj");
 
             _engineEnvironmentSettings.Host.FileSystem.WriteAllText(slnFileFullPath, "");
@@ -314,6 +326,21 @@ public void AddProjectToSolutionFailsWhenSolutionFolderAndInRootSpecified()
             Assert.False(result);
         }
 
+        /// <summary>
+        /// Creates a virtualized path at the root.
+        /// This is used to test the behavior of finding *.slnx files after failing to find *.sln files.
+        ///
+        /// If the root is not virtualized, tests will fail because the "FindFilesAtOrAbovePath" method
+        /// will run into a non-virtualized directory and fail due to it not existing within the "virtual cone".
+        /// </summary>
+        /// <returns>The root path virtualized</returns>
+        private string GetVirtualizedRootPath()
+        {
+            var root = Path.GetPathRoot(Directory.GetCurrentDirectory())!;
+            _engineEnvironmentSettings.Host.VirtualizeDirectory(root);
+            return Path.Combine(Directory.GetCurrentDirectory(), "sandbox", Guid.NewGuid().ToString()) + Path.DirectorySeparatorChar;
+        }
+
         private class MockAddProjectToSolutionCallback
         {
             public string? Solution { get; private set; }