diff --git a/src/Microsoft.Azure.SignalR.Common/Constants.cs b/src/Microsoft.Azure.SignalR.Common/Constants.cs
index 43943a53d..a691ff4be 100644
--- a/src/Microsoft.Azure.SignalR.Common/Constants.cs
+++ b/src/Microsoft.Azure.SignalR.Common/Constants.cs
@@ -107,7 +107,7 @@ public static class Headers
 
         public static class ErrorCodes
         {
-            public const string WarningConnectionsNotExisted = "Warning.Connection.NotExisted";
+            public const string WarningConnectionNotExisted = "Warning.Connection.NotExisted";
             public const string WarningUserNotExisted = "Warning.User.NotExisted";
             public const string WarningGroupNotExisted = "Warning.Group.NotExisted";
             public const string InfoUserNotInGroup = "Info.User.NotInGroup";
diff --git a/src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs b/src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs
index 97e44466b..492169437 100644
--- a/src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs
+++ b/src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs
@@ -248,7 +248,7 @@ public async Task CloseConnectionAsync(string connectionId, string reason, Cance
                 throw new ArgumentException(NullOrEmptyStringErrorMessage, nameof(connectionId));
             }
             var api = await _restApiProvider.GetCloseConnectionEndpointAsync(_appName, _hubName, connectionId, reason);
-            await _restClient.SendAsync(api, HttpMethod.Delete, _productInfo, handleExpectedResponseAsync: null, cancellationToken: cancellationToken);
+            await _restClient.SendAsync(api, HttpMethod.Delete, _productInfo, handleExpectedResponse: static response => FilterExpectedResponse(response, ErrorCodes.WarningConnectionNotExisted), cancellationToken: cancellationToken);
         }
 
         private static void ValidateUserIdAndGroupName(string userId, string groupName)
@@ -275,7 +275,7 @@ public async Task<bool> ConnectionExistsAsync(string connectionId, CancellationT
             await _restClient.SendAsync(api, HttpMethod.Head, _productInfo, handleExpectedResponse: response =>
             {
                 exists = response.StatusCode == HttpStatusCode.OK;
-                return FilterExpectedResponse(response, ErrorCodes.WarningConnectionsNotExisted);
+                return FilterExpectedResponse(response, ErrorCodes.WarningConnectionNotExisted);
             }, cancellationToken: cancellationToken);
             return exists;
         }
diff --git a/test/Microsoft.Azure.SignalR.E2ETests/Management/ServiceHubContextE2EFacts.cs b/test/Microsoft.Azure.SignalR.E2ETests/Management/ServiceHubContextE2EFacts.cs
index eed145752..b2e2129a8 100644
--- a/test/Microsoft.Azure.SignalR.E2ETests/Management/ServiceHubContextE2EFacts.cs
+++ b/test/Microsoft.Azure.SignalR.E2ETests/Management/ServiceHubContextE2EFacts.cs
@@ -816,6 +816,98 @@ public async Task AddNonexistentConnectionToGroupRestApiTest()
             await context.Groups.AddToGroupAsync(Guid.NewGuid().ToString(), "group");
         }
 
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task CloseNonexistentConnectionToGroupRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.ClientManager.CloseConnectionAsync(Guid.NewGuid().ToString());
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task RemoveNonexistentConnectionFromGroupRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.Groups.RemoveFromGroupAsync(Guid.NewGuid().ToString(), "group");
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task RemoveNonexistentConnectionFromAllGroupsRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.Groups.RemoveFromAllGroupsAsync(Guid.NewGuid().ToString());
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task AddNonexistentUserToGroupRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.UserGroups.AddToGroupAsync(Guid.NewGuid().ToString(), Guid.NewGuid().ToString());
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task AddNonexistentUserToGroupWithTTLRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.UserGroups.AddToGroupAsync(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), TimeSpan.Zero);
+            await context.UserGroups.AddToGroupAsync(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), TimeSpan.FromSeconds(1));
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task RemoveNonexistentUserFromGroupRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.UserGroups.RemoveFromGroupAsync(Guid.NewGuid().ToString(), Guid.NewGuid().ToString());
+        }
+
+        [ConditionalFact]
+        [SkipIfConnectionStringNotPresent]
+        public async Task RemoveNonexistentUserFromAllGroupsRestApiTest()
+        {
+            using var serviceManager = new ServiceManagerBuilder().WithOptions(o =>
+            {
+                o.ConnectionString = TestConfiguration.Instance.ConnectionString;
+                o.ServiceTransportType = ServiceTransportType.Transient;
+            }).BuildServiceManager();
+            using var context = await serviceManager.CreateHubContextAsync(HubName, default);
+            await context.UserGroups.RemoveFromAllGroupsAsync(Guid.NewGuid().ToString());
+        }
+
         private static IDictionary<string, List<string>> GenerateUserGroupDict(IList<string> userNames, IList<string> groupNames)
         {
             return (from i in Enumerable.Range(0, userNames.Count)