diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpClientContext.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpClientContext.cs
index 4133c02b82..5270885b62 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpClientContext.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpClientContext.cs
@@ -26,7 +26,7 @@ namespace OSHttpServer
         static private int basecontextID;
 
         Queue<HttpRequest> m_requests;
-        object m_requestsLock = new object();
+        readonly object m_requestsLock = new();
         public int m_maxRequests = MAXREQUESTS;
         public bool m_waitingResponse; 
 
@@ -130,10 +130,10 @@ namespace OSHttpServer
             {
                 SslStream _ssl = (SslStream)m_stream;
                 X509Certificate _cert1 = _ssl.RemoteCertificate;
-                if (_cert1 != null)
+                if (_cert1 is not null)
                 {
-                    X509Certificate2 _cert2 = new X509Certificate2(_cert1);
-                    if (_cert2 != null)
+                    X509Certificate2 _cert2 = new(_cert1);
+                    if (_cert2 is not null)
                         SSLCommonName = _cert2.GetNameInfo(X509NameType.SimpleName, false);
                 }
             }
@@ -150,7 +150,7 @@ namespace OSHttpServer
             if (contextID < 0 || m_isClosing)
                 return false;
 
-            if (m_stream == null || m_sock == null || !m_sock.Connected)
+            if (m_stream is null || m_sock is null || !m_sock.Connected)
                 return false;
 
             return true;
@@ -230,7 +230,7 @@ namespace OSHttpServer
 
             contextID = -100;
 
-            if (m_stream != null)
+            if (m_stream is not null)
             {
                 m_stream.Close();
                 m_stream = null;
@@ -322,7 +322,7 @@ namespace OSHttpServer
             {
                 try
                 {
-                    if (m_stream != null)
+                    if (m_stream is not null)
                     {
                         if (error == SocketError.Success)
                         {
@@ -437,8 +437,8 @@ namespace OSHttpServer
             catch (IOException err)
             {
                 LogWriter.Write(this, LogPrio.Debug, "Failed to end receive: " + err.Message);
-                if (err.InnerException is SocketException)
-                    Disconnect((SocketError)((SocketException)err.InnerException).ErrorCode);
+                if (err.InnerException is SocketException exception)
+                    Disconnect((SocketError)exception.ErrorCode);
                 else
                     Disconnect(SocketError.ConnectionReset);
             }
@@ -466,7 +466,7 @@ namespace OSHttpServer
             FullRequestReceived = true;
             LastActivityTimeMS = ContextTimeoutManager.EnvironmentTickCount();
 
-            if (m_maxRequests <= 0 || RequestReceived == null)
+            if (m_maxRequests <= 0 || RequestReceived is null)
                 return;
 
             if (--m_maxRequests == 0)
@@ -477,7 +477,7 @@ namespace OSHttpServer
                 // should not happen
                 try
                 {
-                    Uri uri = new Uri(m_currentRequest.Secure ? "https://" : "http://" + m_currentRequest.UriPath);
+                    Uri uri = new(m_currentRequest.Secure ? "https://" : "http://" + m_currentRequest.UriPath);
                     m_currentRequest.Uri = uri;
                     m_currentRequest.UriPath = uri.AbsolutePath;
                 }
@@ -641,7 +641,7 @@ namespace OSHttpServer
         /// <exception cref="ArgumentNullException"></exception>
         public bool Send(byte[] buffer)
         {
-            if (buffer == null)
+            if (buffer is null)
                 throw new ArgumentNullException("buffer");
             return Send(buffer, 0, buffer.Length);
         }
@@ -655,7 +655,7 @@ namespace OSHttpServer
         /// <exception cref="ArgumentNullException"></exception>
         /// <exception cref="ArgumentOutOfRangeException"></exception>
 
-        private object sendLock = new object();
+        private readonly object sendLock = new();
 
         public bool Send(byte[] buffer, int offset, int size)
         {
@@ -759,7 +759,7 @@ namespace OSHttpServer
             m_currentRequest = null;
             m_currentResponse?.Clear();
             m_currentResponse = null;
-            if (m_requests != null)
+            if (m_requests is not null)
             {
                 while (m_requests.Count > 0)
                 {
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpContextFactory.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpContextFactory.cs
index e6f4bd7c9d..eed59510aa 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpContextFactory.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpContextFactory.cs
@@ -15,7 +15,7 @@ namespace OSHttpServer
     /// </summary>
     public class HttpContextFactory : IHttpContextFactory
     {
-        private readonly ConcurrentDictionary<int, HttpClientContext> m_activeContexts = new ConcurrentDictionary<int, HttpClientContext>();
+        private readonly ConcurrentDictionary<int, HttpClientContext> m_activeContexts = new();
         private readonly ILogWriter m_logWriter;
 
         /// <summary>
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInput.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInput.cs
index e4701903a3..939377158b 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInput.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInput.cs
@@ -11,8 +11,8 @@ namespace OSHttpServer
     public class HttpInput : IHttpInput
     {
         /// <summary> Representation of a non-initialized class instance </summary>
-        public static readonly HttpInput Empty = new HttpInput("Empty", true);
-        private readonly IDictionary<string, HttpInputItem> _items = new Dictionary<string, HttpInputItem>();
+        public static readonly HttpInput Empty = new("Empty", true);
+        private readonly Dictionary<string, HttpInputItem> _items = new();
         private string _name;
 
         /// <summary> Variable telling the class that it is non-initialized <see cref="Empty"/> </summary>
@@ -70,7 +70,7 @@ namespace OSHttpServer
         /// <exception cref="InvalidOperationException">Cannot add stuff to <see cref="HttpInput.Empty"/>.</exception>
         public void Add(string name, string value)
         {
-            if (name == null)
+            if (name is null)
                 throw new ArgumentNullException("name");
             if (_ignoreChanges)
                 throw new InvalidOperationException("Cannot add stuff to HttpInput.Empty.");
@@ -80,16 +80,19 @@ namespace OSHttpServer
             int pos = name.IndexOf('[');
             if (pos != -1)
             {
-                string name1 = name.Substring(0, pos);
+                string name1 = name[..pos];
                 string name2 = ExtractOne(name);
-                if (!_items.ContainsKey(name1))
-                    _items.Add(name1, new HttpInputItem(name1, null));
-                _items[name1].Add(name2, value);
+                if (!_items.TryGetValue(name1, out HttpInputItem it))
+                {
+                    it = new HttpInputItem(name1, null);
+                    _items.Add(name1, it);
+                }
+                it.Add(name2, value);
             }
             else
             {
-                if (_items.ContainsKey(name))
-                    _items[name].Add(value);
+                if (_items.TryGetValue(name, out HttpInputItem it))
+                    it.Add(value);
                 else
                     _items.Add(name, new HttpInputItem(name, value));
             }
@@ -115,7 +118,7 @@ namespace OSHttpServer
         /// <returns>True if the value exists</returns>
         public bool Contains(string name)
         {
-            return _items.ContainsKey(name) && _items[name].Value != null;
+            return _items.TryGetValue(name, out HttpInputItem it) && it.Value is not null;
         }
 
         /// <summary>
@@ -134,10 +137,12 @@ namespace OSHttpServer
             int pos = name.IndexOf('[');
             if (pos != -1)
             {
-                string name1 = name.Substring(0, pos);
+                string name1 = name[..pos];
                 string name2 = ExtractOne(name);
-                item = new HttpInputItem(name1, null);
-                item.Add(name2, value);
+                item = new HttpInputItem(name1, null)
+                {
+                    { name2, value }
+                };
             }
             else
                 item = new HttpInputItem(name, value);
@@ -166,7 +171,7 @@ namespace OSHttpServer
             foreach (KeyValuePair<string, HttpInputItem> item in _items)
                 temp += item.Value.ToString(null, true) + '&';
 
-            return temp.Length > 0 ? temp.Substring(0, temp.Length - 1) : string.Empty;
+            return temp.Length > 0 ? temp[..^1] : string.Empty;
         }
 
         /// <summary>
@@ -190,7 +195,7 @@ namespace OSHttpServer
                 ++pos;
                 int gotMore = value.IndexOf('[', pos + 1);
                 if (gotMore != -1)
-                    value = value.Substring(pos, gotMore - pos - 1) + value.Substring(gotMore);
+                    value = string.Concat(value.AsSpan(pos, gotMore - pos - 1), value.AsSpan(gotMore));
                 else
                     value = value.Substring(pos, value.Length - pos - 1);
             }
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
index 2172c7da52..2a3fb37dfb 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpInputItem.cs
@@ -18,9 +18,9 @@ namespace OSHttpServer
     public class HttpInputItem : IHttpInput
     {
         /// <summary> Representation of a non-initialized <see cref="HttpInputItem"/>.</summary>
-        public static readonly HttpInputItem Empty = new HttpInputItem(string.Empty, true);
+        public static readonly HttpInputItem Empty = new(string.Empty, true);
         private readonly IDictionary<string, HttpInputItem> _items = new Dictionary<string, HttpInputItem>();
-        private readonly List<string> _values = new List<string>();
+        private readonly List<string> _values = new();
         private string _name;
         private readonly bool _ignoreChanges;
         
@@ -109,7 +109,7 @@ namespace OSHttpServer
         {
             get
             {
-                return _values.Count == 0 ? null : _values[_values.Count - 1];
+                return _values.Count == 0 ? null : _values[^1];
             }
         }
 
@@ -129,7 +129,7 @@ namespace OSHttpServer
         /// <exception cref="InvalidOperationException">Cannot add stuff to <see cref="HttpInput.Empty"/>.</exception>
         public void Add(string value)
         {
-            if (value == null)
+            if (value is null)
                 return;
             if (_ignoreChanges)
                 throw new InvalidOperationException("Cannot add stuff to HttpInput.Empty.");
@@ -185,7 +185,7 @@ namespace OSHttpServer
                 foreach (KeyValuePair<string, HttpInputItem> item in _items)
                     temp += item.Value.ToString(name, true) + '&';
 
-                return _items.Count > 0 ? temp.Substring(0, temp.Length - 1) : temp;
+                return _items.Count > 0 ? temp[..^1] : temp;
             }
             else
             {
@@ -239,11 +239,15 @@ namespace OSHttpServer
             int pos = name.IndexOf('[');
             if (pos != -1)
             {
-                string name1 = name.Substring(0, pos);
+                string name1 = name[..pos];
                 string name2 = HttpInput.ExtractOne(name);
-                if (!_items.ContainsKey(name1))
-                    _items.Add(name1, new HttpInputItem(name1, null));
-                _items[name1].Add(name2, value);
+                if (!_items.TryGetValue(name1, out HttpInputItem it))
+                {
+                    it = new HttpInputItem(name1, null);
+                    _items.Add(name1, it);
+                }                  
+                it.Add(name2, value);
+
                 /*
                 HttpInputItem item = HttpInput.ParseItem(name, value);
 
@@ -256,8 +260,8 @@ namespace OSHttpServer
             }
             else
             {
-                if (_items.ContainsKey(name))
-                    _items[name].Add(value);
+                if (_items.TryGetValue(name, out HttpInputItem it2))
+                    it2.Add(value);
                 else
                     _items.Add(name, new HttpInputItem(name, value));
             }
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpRequest.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpRequest.cs
index 5b69562b03..d0ed6677e3 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpRequest.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpRequest.cs
@@ -22,8 +22,8 @@ namespace OSHttpServer
         public static readonly char[] UriSplitters = new[] { '/' };
         public static uint baseID = 0;
 
-        private readonly NameValueCollection m_headers = new NameValueCollection();
-        private readonly HttpParam m_param = new HttpParam(HttpInput.Empty, HttpInput.Empty);
+        private readonly NameValueCollection m_headers = new();
+        //private readonly HttpParam m_param = new(HttpInput.Empty, HttpInput.Empty);
         private Stream m_body = new MemoryStream();
         private int m_bodyBytesLeft;
         private ConnectionType m_connection = ConnectionType.KeepAlive;
@@ -151,9 +151,9 @@ namespace OSHttpServer
         {
             get
             {
-                if(m_queryString == null)
+                if(m_queryString is null)
                 {
-                    if(m_uri == null || m_uri.Query.Length == 0)
+                    if(m_uri is null || m_uri.Query.Length == 0)
                         m_queryString = new NameValueCollection();
                     else
                     {
@@ -169,7 +169,7 @@ namespace OSHttpServer
             }
         }
 
-        public static readonly Uri EmptyUri = new Uri("http://localhost/");
+        public static readonly Uri EmptyUri = new("http://localhost/");
         /// <summary>
         /// Gets or sets requested URI.
         /// </summary>
@@ -179,6 +179,7 @@ namespace OSHttpServer
             set { m_uri = value ?? EmptyUri; } // not safe
         }
 
+        /*
         /// <summary>
         /// Gets parameter from <see cref="QueryString"/> or <see cref="Form"/>.
         /// </summary>
@@ -186,6 +187,7 @@ namespace OSHttpServer
         {
             get { return m_param; }
         }
+        */
 
         /// <summary>
         /// Gets form parameters.
@@ -219,16 +221,18 @@ namespace OSHttpServer
         {
             // this method was mainly created for testing.
             // dont use it that much...
-            var request = new HttpRequest(Context);
-            request.Method = m_method;
+            var request = new HttpRequest(Context)
+            {
+                Method = m_method,
+                m_httpVersion = m_httpVersion,
+                m_queryString = m_queryString,
+                Uri = m_uri
+            };
             if (AcceptTypes != null)
             {
                 request.AcceptTypes = new string[AcceptTypes.Length];
                 AcceptTypes.CopyTo(request.AcceptTypes, 0);
             }
-            request.m_httpVersion = m_httpVersion;
-            request.m_queryString = m_queryString;
-            request.Uri = m_uri;
 
             var buffer = new byte[m_body.Length];
             m_body.Read(buffer, 0, (int)m_body.Length);
@@ -296,8 +300,7 @@ namespace OSHttpServer
                         }
                     }
                 }
-                if (m_remoteIPEndPoint == null)
-                    m_remoteIPEndPoint = m_context.LocalIPEndPoint;
+                m_remoteIPEndPoint ??= m_context.LocalIPEndPoint;
 
                 return m_remoteIPEndPoint;
             }
@@ -375,7 +378,7 @@ namespace OSHttpServer
                             int indx = s.IndexOf("=", 3);
                             if(indx < 0 || indx >= s.Length - 1)
                                 continue;
-                            s = s.Substring(indx);
+                            s = s[indx..];
                             addr = s.Trim();
                         }
                     }
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpResponse.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpResponse.cs
index 73f87998f6..e20d8ab7ba 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpResponse.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/HttpResponse.cs
@@ -11,8 +11,8 @@ namespace OSHttpServer
     {
         private const string DefaultContentType = "text/html;charset=UTF-8";
         private readonly IHttpClientContext m_context;
-        private readonly ResponseCookies m_cookies = new ResponseCookies();
-        private readonly NameValueCollection m_headers = new NameValueCollection();
+        private readonly ResponseCookies m_cookies = new();
+        private readonly NameValueCollection m_headers = new();
         private string m_httpVersion;
         private Stream m_body;
         private long m_contentLength;
@@ -86,8 +86,7 @@ namespace OSHttpServer
         {
             get
             { 
-                if(m_body == null)
-                    m_body = new MemoryStream();
+                m_body ??= new MemoryStream();
                 return m_body;
             }
         }
@@ -245,13 +244,13 @@ namespace OSHttpServer
             sb.AppendFormat("Date: {0}\r\n", DateTime.Now.ToString("r"));
 
             long len = 0;
-            if(m_body!= null)
+            if(m_body is not null)
                 len = m_body.Length;
-            if (RawBuffer != null && RawBufferLen > 0)
+            if (RawBuffer is not null && RawBufferLen > 0)
                 len += RawBufferLen;
             sb.AppendFormat("Content-Length: {0}\r\n", len);
 
-            if (m_headers["Content-Type"] == null)
+            if (m_headers["Content-Type"] is null)
                 sb.AppendFormat("Content-Type: {0}\r\n", m_contentType ?? DefaultContentType);
 
             switch(Status)
@@ -295,7 +294,7 @@ namespace OSHttpServer
                         continue;
                 }
                 string[] values = m_headers.GetValues(i);
-                if (values == null) continue;
+                if (values is null) continue;
                 foreach (string value in values)
                     sb.AppendFormat("{0}: {1}\r\n", headerName, value);
             }
@@ -331,7 +330,7 @@ namespace OSHttpServer
                     m_context.TimeoutKeepAlive = m_keepAlive * 1000;
             }
 
-            if (RawBuffer != null)
+            if (RawBuffer is not null)
             {
                 if (RawBufferStart > RawBuffer.Length)
                     return;
@@ -348,7 +347,7 @@ namespace OSHttpServer
 
             m_headerBytes = GetHeaders();
 
-            if (RawBuffer != null && RawBufferLen > 0)
+            if (RawBuffer is not null && RawBufferLen > 0)
             {
                 int tlen = m_headerBytes.Length + RawBufferLen;
                 if(tlen < 8 * 1024)
@@ -366,13 +365,13 @@ namespace OSHttpServer
                     RawBuffer = null;
             }
 
-            if (m_body != null && m_body.Length == 0)
+            if (m_body is not null && m_body.Length == 0)
             {
                 m_body.Dispose();
                 m_body = null;
             }
 
-            if (m_headerBytes == null && RawBuffer == null && m_body == null)
+            if (m_headerBytes is null && RawBuffer is null && m_body is null)
             {
                 Sent = true;
                 m_context.EndSendResponse(requestID, Connection);
@@ -383,14 +382,14 @@ namespace OSHttpServer
 
         public bool SendNextAsync(int bytesLimit)
         {
-            if (m_headerBytes != null)
+            if (m_headerBytes is not null)
             {
                 byte[] b = m_headerBytes;
                 m_headerBytes = null;
 
                 if (!m_context.SendAsyncStart(b, 0, b.Length))
                 {
-                    if (m_body != null)
+                    if (m_body is not null)
                     {
                         m_body.Dispose();
                         m_body = null;
@@ -403,7 +402,7 @@ namespace OSHttpServer
             }
 
             bool sendRes;
-            if (RawBuffer != null)
+            if (RawBuffer is not null)
             {
                 if(RawBufferLen > 0)
                 {
@@ -429,7 +428,7 @@ namespace OSHttpServer
                     if (!sendRes)
                     {
                         RawBuffer = null;
-                        if(m_body != null)
+                        if(m_body is not null)
                         {
                             m_body.Dispose();
                             m_body = null;
@@ -443,7 +442,7 @@ namespace OSHttpServer
                     RawBuffer = null;
             }
 
-            if (m_body != null)
+            if (m_body is not null)
             {
                 if(m_body.Length != 0)
                 {
@@ -500,7 +499,7 @@ namespace OSHttpServer
 
         public void CheckSendNextAsyncContinue()
         {
-            if(m_headerBytes == null && RawBuffer == null && m_body == null)
+            if(m_headerBytes is null && RawBuffer is null && m_body is null)
             {
                 Sent = true;
                 m_context.EndSendResponse(requestID, Connection);
@@ -513,8 +512,12 @@ namespace OSHttpServer
 
         public void Clear()
         {
-            if(m_body != null && m_body.CanRead)
+            if(m_body is not null && m_body.CanRead)
+            {
                 m_body.Dispose();
+                m_body = null;
+            }
+            RawBuffer = null;
         }
         #endregion
     }
diff --git a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/IHttpRequest.cs b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/IHttpRequest.cs
index 2ca5f4e1be..8a12febc58 100644
--- a/OpenSim/Framework/Servers/HttpServer/OSHttpServer/IHttpRequest.cs
+++ b/OpenSim/Framework/Servers/HttpServer/OSHttpServer/IHttpRequest.cs
@@ -72,10 +72,12 @@ namespace OSHttpServer
         /// <see cref="Method"/>
         string Method { get; set; }
 
+        /*
         /// <summary>
         /// Gets parameter from <see cref="QueryString"/> or <see cref="Form"/>.
         /// </summary>
         HttpParam Param { get; }
+        */
 
         /// <summary>
         /// Gets variables sent in the query string
diff --git a/OpenSim/Server/Handlers/Inventory/XInventoryInConnector.cs b/OpenSim/Server/Handlers/Inventory/XInventoryInConnector.cs
index 080a458a5a..b39c9bfd27 100644
--- a/OpenSim/Server/Handlers/Inventory/XInventoryInConnector.cs
+++ b/OpenSim/Server/Handlers/Inventory/XInventoryInConnector.cs
@@ -583,14 +583,19 @@ namespace OpenSim.Server.Handlers.Inventory
         byte[] HandleGetMultipleItems(Dictionary<string, object> request)
         {
             Dictionary<string, object> resultSet = new Dictionary<string, object>();
-            UUID principal = UUID.Zero;
-            UUID.TryParse(request["PRINCIPAL"].ToString(), out principal);
-            string itemIDstr = request["ITEMS"].ToString();
-            int count = 0;
-            Int32.TryParse(request["COUNT"].ToString(), out count);
 
-            UUID[] fids = new UUID[count];
+            if(!UUID.TryParse(request["PRINCIPAL"].ToString(), out UUID principal))
+                return Util.UTF8NoBomEncoding.GetBytes(ServerUtils.BuildXmlResponse(resultSet));
+
+            string itemIDstr = request["ITEMS"].ToString();
+            if(string.IsNullOrEmpty(itemIDstr))
+                return Util.UTF8NoBomEncoding.GetBytes(ServerUtils.BuildXmlResponse(resultSet));
+
             string[] uuids = itemIDstr.Split(',');
+            if(uuids.Length == 0)
+                return Util.UTF8NoBomEncoding.GetBytes(ServerUtils.BuildXmlResponse(resultSet));
+
+            UUID[] fids = new UUID[uuids.Length];
             int i = 0;
             foreach (string id in uuids)
             {
@@ -603,9 +608,9 @@ namespace OpenSim.Server.Handlers.Inventory
             InventoryItemBase[] itemsList = m_InventoryService.GetMultipleItems(principal, fids);
             if (itemsList != null && itemsList.Length > 0)
             {
-                count = 0;
+                int count = 0;
                 foreach (InventoryItemBase item in itemsList)
-                    resultSet["item_" + count++] = (item == null) ? (object)"NULL" : EncodeItem(item);
+                    resultSet["item_" + count++] = (item == null) ? "NULL" : EncodeItem(item);
             }
 
             string xmlString = ServerUtils.BuildXmlResponse(resultSet);