diff --git a/.gitignore b/.gitignore
index 4462784..c6c5991 100644
--- a/.gitignore
+++ b/.gitignore
@@ -355,4 +355,7 @@ App_Data/
 
 # Modules
 */Stott.Optimizely.RobotsHandler/modules/**
-*/OptimizelyTwelveTest/modules/**
\ No newline at end of file
+*/OptimizelyTwelveTest/modules/**
+
+# Settings
+appsettings.Development.json
\ No newline at end of file
diff --git a/Sample/OptimizelyTwelveTest/appsettings.Development.json b/Sample/OptimizelyTwelveTest/appsettings.Development.json
deleted file mode 100644
index 332487d..0000000
--- a/Sample/OptimizelyTwelveTest/appsettings.Development.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-  "Logging": {
-    "LogLevel": {
-      "Default": "Information",
-      "Microsoft": "Warning",
-      "EPiServer": "Warning",
-      "Microsoft.Hosting.Lifetime": "Information"
-    }
-  },
-  "urls": "http://*:8000/;https://*:8001/;",
-  "AllowedHosts": "*"
-}
\ No newline at end of file
diff --git a/src/Stott.Optimizely.RobotsHandler.Test/Llms/LlmsApiControllerTests.cs b/src/Stott.Optimizely.RobotsHandler.Test/Llms/LlmsApiControllerTests.cs
index b81b6fb..ce717fc 100644
--- a/src/Stott.Optimizely.RobotsHandler.Test/Llms/LlmsApiControllerTests.cs
+++ b/src/Stott.Optimizely.RobotsHandler.Test/Llms/LlmsApiControllerTests.cs
@@ -79,7 +79,7 @@ public void Details_RetrievesDefaultModelWhenPresentedWithAnEmptyId()
     public void Save_ReturnsConflictResultWhenConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveLlmsModel();
+        var formSubmitModel = new SaveLlmsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>())).Returns(true);
 
@@ -95,7 +95,7 @@ public void Save_ReturnsConflictResultWhenConflictExists()
     public void Save_DoesNotSaveModelWhenConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveLlmsModel();
+        var formSubmitModel = new SaveLlmsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>())).Returns(true);
 
@@ -110,7 +110,7 @@ public void Save_DoesNotSaveModelWhenConflictExists()
     public void Save_SavesModelWhenNoConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveLlmsModel();
+        var formSubmitModel = new SaveLlmsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>())).Returns(false);
 
@@ -125,7 +125,7 @@ public void Save_SavesModelWhenNoConflictExists()
     public void Save_WhenDoesConflictExistsThrowsAnException_ThenAnInternalServerErrorIsReturned()
     {
         // Arrange
-        var formSubmitModel = new SaveLlmsModel();
+        var formSubmitModel = new SaveLlmsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>())).Throws<Exception>();
 
@@ -141,7 +141,7 @@ public void Save_WhenDoesConflictExistsThrowsAnException_ThenAnInternalServerErr
     public void Save_WhenSaveOnTheServiceThrowsAnException_ThenAnInternalServerErrorIsReturned()
     {
         // Arrange
-        var formSubmitModel = new SaveLlmsModel();
+        var formSubmitModel = new SaveLlmsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>())).Returns(false);
         _mockService.Setup(x => x.Save(It.IsAny<SaveLlmsModel>())).Throws<Exception>();
@@ -154,6 +154,36 @@ public void Save_WhenSaveOnTheServiceThrowsAnException_ThenAnInternalServerError
         Assert.That(((ContentResult)result).StatusCode, Is.EqualTo(500));
     }
 
+    [Test]
+    [TestCaseSource(typeof(CommonTestCases), nameof(CommonTestCases.EmptyStrings))]
+    public void Save_WhenAppIdIsMissing_ReturnsABadRequest(string appId)
+    {
+        // Arrange
+        var formSubmitModel = new SaveLlmsModel { AppId = appId };
+
+        // Act
+        var result = _controller.Save(formSubmitModel);
+
+        // Assert
+        Assert.That(result, Is.AssignableFrom<ContentResult>());
+        Assert.That(((ContentResult)result).StatusCode, Is.EqualTo(400));
+    }
+
+    [Test]
+    [TestCaseSource(typeof(CommonTestCases), nameof(CommonTestCases.EmptyStrings))]
+    public void Save_WhenAppIdIsMissing_DoesNotCheckForConflictsOrSave(string appId)
+    {
+        // Arrange
+        var formSubmitModel = new SaveLlmsModel { AppId = appId };
+
+        // Act
+        _controller.Save(formSubmitModel);
+
+        // Assert
+        _mockService.Verify(x => x.DoesConflictExists(It.IsAny<SaveLlmsModel>()), Times.Never);
+        _mockService.Verify(x => x.Save(It.IsAny<SaveLlmsModel>()), Times.Never);
+    }
+
     [Test]
     public void Delete_WhenGivenAnEmptyId_ReturnsABadRequest()
     {
diff --git a/src/Stott.Optimizely.RobotsHandler.Test/Robots/RobotsApiControllerTests.cs b/src/Stott.Optimizely.RobotsHandler.Test/Robots/RobotsApiControllerTests.cs
index 88a4ac0..e67897d 100644
--- a/src/Stott.Optimizely.RobotsHandler.Test/Robots/RobotsApiControllerTests.cs
+++ b/src/Stott.Optimizely.RobotsHandler.Test/Robots/RobotsApiControllerTests.cs
@@ -79,7 +79,7 @@ public void Details_RetrievesDefaultModelWhenPresentedWithAnEmptyId()
     public void Save_ReturnsConflictResultWhenConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveRobotsModel();
+        var formSubmitModel = new SaveRobotsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>())).Returns(true);
 
@@ -95,7 +95,7 @@ public void Save_ReturnsConflictResultWhenConflictExists()
     public void Save_DoesNotSaveModelWhenConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveRobotsModel();
+        var formSubmitModel = new SaveRobotsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>())).Returns(true);
 
@@ -110,7 +110,7 @@ public void Save_DoesNotSaveModelWhenConflictExists()
     public void Save_SavesModelWhenNoConflictExists()
     {
         // Arrange
-        var formSubmitModel = new SaveRobotsModel();
+        var formSubmitModel = new SaveRobotsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>())).Returns(false);
 
@@ -125,7 +125,7 @@ public void Save_SavesModelWhenNoConflictExists()
     public void Save_WhenDoesConflictExistsThrowsAnException_ThenAnInternalServerErrorIsReturned()
     {
         // Arrange
-        var formSubmitModel = new SaveRobotsModel();
+        var formSubmitModel = new SaveRobotsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>())).Throws<Exception>();
 
@@ -141,7 +141,7 @@ public void Save_WhenDoesConflictExistsThrowsAnException_ThenAnInternalServerErr
     public void Save_WhenSaveOnTheServiceThrowsAnException_ThenAnInternalServerErrorIsReturned()
     {
         // Arrange
-        var formSubmitModel = new SaveRobotsModel();
+        var formSubmitModel = new SaveRobotsModel { AppId = "MyApp" };
 
         _mockService.Setup(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>())).Returns(false);
         _mockService.Setup(x => x.Save(It.IsAny<SaveRobotsModel>())).Throws<Exception>();
@@ -154,6 +154,36 @@ public void Save_WhenSaveOnTheServiceThrowsAnException_ThenAnInternalServerError
         Assert.That(((ContentResult)result).StatusCode, Is.EqualTo(500));
     }
 
+    [Test]
+    [TestCaseSource(typeof(CommonTestCases), nameof(CommonTestCases.EmptyStrings))]
+    public void Save_WhenAppIdIsMissing_ReturnsABadRequest(string appId)
+    {
+        // Arrange
+        var formSubmitModel = new SaveRobotsModel { AppId = appId };
+
+        // Act
+        var result = _controller.Save(formSubmitModel);
+
+        // Assert
+        Assert.That(result, Is.AssignableFrom<ContentResult>());
+        Assert.That(((ContentResult)result).StatusCode, Is.EqualTo(400));
+    }
+
+    [Test]
+    [TestCaseSource(typeof(CommonTestCases), nameof(CommonTestCases.EmptyStrings))]
+    public void Save_WhenAppIdIsMissing_DoesNotCheckForConflictsOrSave(string appId)
+    {
+        // Arrange
+        var formSubmitModel = new SaveRobotsModel { AppId = appId };
+
+        // Act
+        _controller.Save(formSubmitModel);
+
+        // Assert
+        _mockService.Verify(x => x.DoesConflictExists(It.IsAny<SaveRobotsModel>()), Times.Never);
+        _mockService.Verify(x => x.Save(It.IsAny<SaveRobotsModel>()), Times.Never);
+    }
+
     [Test]
     public void Delete_WhenGivenAnEmptyId_ReturnsABadRequest()
     {
diff --git a/src/Stott.Optimizely.RobotsHandler.Ui/src/AddSiteLlms.jsx b/src/Stott.Optimizely.RobotsHandler.Ui/src/AddSiteLlms.jsx
index 299931c..b304db9 100644
--- a/src/Stott.Optimizely.RobotsHandler.Ui/src/AddSiteLlms.jsx
+++ b/src/Stott.Optimizely.RobotsHandler.Ui/src/AddSiteLlms.jsx
@@ -169,7 +169,7 @@ Optional details go here
                     <Modal.Title>Create LLMS Configuration</Modal.Title>
                 </Modal.Header>
                 <Modal.Body>
-                <div className='mb-3'>
+                    <div className='mb-3'>
                         <label>Application</label>
                         <select className='form-control form-select' name='SpecificHost' onChange={handleAppSelection}>{renderAvailableApps()}</select>
                     </div>
diff --git a/src/Stott.Optimizely.RobotsHandler/Applications/ApplicationDefinitionController.cs b/src/Stott.Optimizely.RobotsHandler/Applications/ApplicationDefinitionController.cs
index f5daf07..43dba0c 100644
--- a/src/Stott.Optimizely.RobotsHandler/Applications/ApplicationDefinitionController.cs
+++ b/src/Stott.Optimizely.RobotsHandler/Applications/ApplicationDefinitionController.cs
@@ -1,5 +1,4 @@
-using System.Linq;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
@@ -17,14 +16,7 @@ public sealed class ApplicationDefinitionController(IApplicationDefinitionServic
     public async Task<IActionResult> Applications()
     {
         var apps = await appService.GetAllApplicationsAsync();
-        var allApps = apps.ToList();
 
-        allApps.Insert(0, new ApplicationViewModel
-        {
-            AppName = "All Applications",
-            AvailableHosts = ApplicationMapper.CreateHostSummaries("All Hosts")
-        });
-
-        return CreateSafeJsonResult(allApps);
+        return CreateSafeJsonResult(apps);
     }
 }
diff --git a/src/Stott.Optimizely.RobotsHandler/Llms/DefaultLlmsContentService.cs b/src/Stott.Optimizely.RobotsHandler/Llms/DefaultLlmsContentService.cs
index 6ce39ff..871e99c 100644
--- a/src/Stott.Optimizely.RobotsHandler/Llms/DefaultLlmsContentService.cs
+++ b/src/Stott.Optimizely.RobotsHandler/Llms/DefaultLlmsContentService.cs
@@ -92,7 +92,7 @@ public ApplicationLlmsViewModel GetDefault(string? appId)
 
     public void Save(SaveLlmsModel model)
     {
-        if (Guid.Empty.Equals(model.AppId))
+        if (string.IsNullOrWhiteSpace(model.AppId))
         {
             throw new ArgumentException($"{nameof(model)}.{nameof(model.AppId)} must not be null or empty.", nameof(model));
         }
diff --git a/src/Stott.Optimizely.RobotsHandler/Llms/LlmsApiController.cs b/src/Stott.Optimizely.RobotsHandler/Llms/LlmsApiController.cs
index 4c88bd3..bb0a09d 100644
--- a/src/Stott.Optimizely.RobotsHandler/Llms/LlmsApiController.cs
+++ b/src/Stott.Optimizely.RobotsHandler/Llms/LlmsApiController.cs
@@ -52,6 +52,16 @@ public IActionResult Save(SaveLlmsModel formSubmitModel)
     {
         try
         {
+            if (string.IsNullOrWhiteSpace(formSubmitModel.AppId))
+            {
+                return new ContentResult
+                {
+                    StatusCode = (int)HttpStatusCode.BadRequest,
+                    Content = $"{nameof(formSubmitModel.AppId)} does not have a value.",
+                    ContentType = "text/plain"
+                };
+            }
+
             if (service.DoesConflictExists(formSubmitModel))
             {
                 return new ContentResult
diff --git a/src/Stott.Optimizely.RobotsHandler/Robots/RobotsApiController.cs b/src/Stott.Optimizely.RobotsHandler/Robots/RobotsApiController.cs
index 8f47257..64860c4 100644
--- a/src/Stott.Optimizely.RobotsHandler/Robots/RobotsApiController.cs
+++ b/src/Stott.Optimizely.RobotsHandler/Robots/RobotsApiController.cs
@@ -52,6 +52,16 @@ public IActionResult Save(SaveRobotsModel formSubmitModel)
     {
         try
         {
+            if (string.IsNullOrWhiteSpace(formSubmitModel.AppId))
+            {
+                return new ContentResult
+                {
+                    StatusCode = (int)HttpStatusCode.BadRequest,
+                    Content = $"{nameof(formSubmitModel.AppId)} does not have a value.",
+                    ContentType = "text/plain"
+                };
+            }
+
             if (service.DoesConflictExists(formSubmitModel))
             {
                 return new ContentResult
diff --git a/src/Stott.Optimizely.RobotsHandler/Robots/RobotsContentService.cs b/src/Stott.Optimizely.RobotsHandler/Robots/RobotsContentService.cs
index f728e8d..02c5e59 100644
--- a/src/Stott.Optimizely.RobotsHandler/Robots/RobotsContentService.cs
+++ b/src/Stott.Optimizely.RobotsHandler/Robots/RobotsContentService.cs
@@ -94,7 +94,7 @@ public SiteRobotsViewModel GetDefault(string? appId)
 
     public void Save(SaveRobotsModel model)
     {
-        if (Guid.Empty.Equals(model.AppId))
+        if (string.IsNullOrWhiteSpace(model.AppId))
         {
             throw new ArgumentException($"{nameof(model)}.{nameof(model.AppId)} must not be null or empty.", nameof(model));
         }