diff --git a/src/SoapCore.Tests/Wsdl/WsdlTests.cs b/src/SoapCore.Tests/Wsdl/WsdlTests.cs
index 0d5d6d3a..b0f989d5 100644
--- a/src/SoapCore.Tests/Wsdl/WsdlTests.cs
+++ b/src/SoapCore.Tests/Wsdl/WsdlTests.cs
@@ -742,7 +742,7 @@ private async Task<string> GetWsdlFromMetaBodyWriter<T>(SoapSerializer serialize
 			var bodyWriter = serializer == SoapSerializer.DataContractSerializer
 				? new MetaWCFBodyWriter(service, baseUrl, "BasicHttpBinding", false) as BodyWriter
 				: new MetaBodyWriter(service, baseUrl, xmlNamespaceManager, "BasicHttpBinding", new[] { MessageVersion.None }) as BodyWriter;
-			var encoder = new SoapMessageEncoder(MessageVersion.Soap12WSAddressingAugust2004, System.Text.Encoding.UTF8, XmlDictionaryReaderQuotas.Max, false, true);
+			var encoder = new SoapMessageEncoder(MessageVersion.Soap12WSAddressingAugust2004, System.Text.Encoding.UTF8, XmlDictionaryReaderQuotas.Max, false, true, false);
 			var responseMessage = Message.CreateMessage(encoder.MessageVersion, null, bodyWriter);
 			responseMessage = new MetaMessage(responseMessage, service, xmlNamespaceManager, "BasicHttpBinding", false);
 
diff --git a/src/SoapCore/MessageEncoder/SoapMessageEncoder.cs b/src/SoapCore/MessageEncoder/SoapMessageEncoder.cs
index ca2a254a..9b4aaddf 100644
--- a/src/SoapCore/MessageEncoder/SoapMessageEncoder.cs
+++ b/src/SoapCore/MessageEncoder/SoapMessageEncoder.cs
@@ -28,11 +28,13 @@ public class SoapMessageEncoder
 		private readonly bool _omitXmlDeclaration;
 		private readonly bool _indentXml;
 		private readonly bool _supportXmlDictionaryReader;
+		private readonly bool _checkXmlCharacters;
 
-		public SoapMessageEncoder(MessageVersion version, Encoding writeEncoding, XmlDictionaryReaderQuotas quotas, bool omitXmlDeclaration, bool indentXml)
+		public SoapMessageEncoder(MessageVersion version, Encoding writeEncoding, XmlDictionaryReaderQuotas quotas, bool omitXmlDeclaration, bool indentXml, bool checkXmlCharacters)
 		{
 			_indentXml = indentXml;
 			_omitXmlDeclaration = omitXmlDeclaration;
+			_checkXmlCharacters = checkXmlCharacters;
 			if (writeEncoding == null)
 			{
 				throw new ArgumentNullException(nameof(writeEncoding));
@@ -153,7 +155,8 @@ public virtual async Task WriteMessageAsync(Message message, PipeWriter pipeWrit
 				OmitXmlDeclaration = _optimizeWriteForUtf8 && _omitXmlDeclaration, //can only omit if utf-8
 				Indent = _indentXml,
 				Encoding = _writeEncoding,
-				CloseOutput = true
+				CloseOutput = true,
+				CheckCharacters = _checkXmlCharacters
 			});
 
 			using var xmlWriter = XmlDictionaryWriter.CreateDictionaryWriter(xmlTextWriter);
@@ -183,7 +186,8 @@ public virtual Task WriteMessageAsync(Message message, Stream stream)
 				OmitXmlDeclaration = _optimizeWriteForUtf8 && _omitXmlDeclaration, //can only omit if utf-8,
 				Indent = _indentXml,
 				Encoding = _writeEncoding,
-				CloseOutput = false
+				CloseOutput = false,
+				CheckCharacters = _checkXmlCharacters
 			});
 
 			using var xmlWriter = XmlDictionaryWriter.CreateDictionaryWriter(xmlTextWriter);
diff --git a/src/SoapCore/SoapCoreOptions.cs b/src/SoapCore/SoapCoreOptions.cs
index 1e2ef409..bfad83fc 100644
--- a/src/SoapCore/SoapCoreOptions.cs
+++ b/src/SoapCore/SoapCoreOptions.cs
@@ -86,6 +86,12 @@ public class SoapCoreOptions
 		/// </summary>
 		public bool IndentXml { get; set; } = true;
 
+		/// <summary>
+		/// Gets or sets a value indicating whether to check to make sure that the XmlOutput doesn't contain invalid characters
+		/// <para>Defaults to true</para>
+		/// </summary>
+		public bool CheckXmlCharacters { get; set; } = true;
+
 		/// <summary>
 		/// Gets or sets an collection of Xml Namespaces to override the default prefix for.
 		/// </summary>
diff --git a/src/SoapCore/SoapEndpointMiddleware.cs b/src/SoapCore/SoapEndpointMiddleware.cs
index 8e34a2ff..3b05b0d4 100644
--- a/src/SoapCore/SoapEndpointMiddleware.cs
+++ b/src/SoapCore/SoapEndpointMiddleware.cs
@@ -69,7 +69,7 @@ public SoapEndpointMiddleware(ILogger<SoapEndpointMiddleware<T_MESSAGE>> logger,
 
 			for (var i = 0; i < options.EncoderOptions.Length; i++)
 			{
-				_messageEncoders[i] = new SoapMessageEncoder(options.EncoderOptions[i].MessageVersion, options.EncoderOptions[i].WriteEncoding, options.EncoderOptions[i].ReaderQuotas, options.OmitXmlDeclaration, options.IndentXml);
+				_messageEncoders[i] = new SoapMessageEncoder(options.EncoderOptions[i].MessageVersion, options.EncoderOptions[i].WriteEncoding, options.EncoderOptions[i].ReaderQuotas, options.OmitXmlDeclaration, options.IndentXml, options.CheckXmlCharacters);
 			}
 		}
 
@@ -686,9 +686,12 @@ private async Task<Message> WriteErrorResponseMessage(
 			var faultExceptionTransformer = serviceProvider.GetRequiredService<IFaultExceptionTransformer>();
 			var faultMessage = faultExceptionTransformer.ProvideFault(exception, messageEncoder.MessageVersion, requestMessage, xmlNamespaceManager);
 
-			httpContext.Response.ContentType = httpContext.Request.ContentType;
-			httpContext.Response.Headers["SOAPAction"] = faultMessage.Headers.Action;
-			httpContext.Response.StatusCode = statusCode;
+			if(!httpContext.Response.HasStarted)
+			{
+				httpContext.Response.ContentType = httpContext.Request.ContentType;
+				httpContext.Response.Headers["SOAPAction"] = faultMessage.Headers.Action;
+				httpContext.Response.StatusCode = statusCode;
+			}
 
 			SetHttpResponse(httpContext, faultMessage);
 			if (messageEncoder.MessageVersion.Addressing == AddressingVersion.WSAddressing10)
diff --git a/src/SoapCore/SoapOptions.cs b/src/SoapCore/SoapOptions.cs
index 15a8b99c..8c082359 100644
--- a/src/SoapCore/SoapOptions.cs
+++ b/src/SoapCore/SoapOptions.cs
@@ -41,6 +41,12 @@ public class SoapOptions
 
 		public bool IndentXml { get; set; } = true;
 
+		/// <summary>
+		/// Gets or sets a value indicating whether to check to make sure that the XmlOutput doesn't contain invalid characters
+		/// <para>Defaults to true</para>
+		/// </summary>
+		public bool CheckXmlCharacters { get; set; } = true;
+
 		public XmlNamespaceManager XmlNamespacePrefixOverrides { get; set; }
 		public WsdlFileOptions WsdlFileOptions { get; set; }
 
@@ -66,7 +72,8 @@ public static SoapOptions FromSoapCoreOptions(SoapCoreOptions opt, Type serviceT
 				OmitXmlDeclaration = opt.OmitXmlDeclaration,
 				IndentXml = opt.IndentXml,
 				XmlNamespacePrefixOverrides = opt.XmlNamespacePrefixOverrides,
-				WsdlFileOptions = opt.WsdlFileOptions
+				WsdlFileOptions = opt.WsdlFileOptions,
+				CheckXmlCharacters = opt.CheckXmlCharacters
 			};
 
 #pragma warning disable CS0612 // Type or member is obsolete