diff --git a/src/SoapCore.Tests/InvalidXMLTests.cs b/src/SoapCore.Tests/InvalidXMLTests.cs
index 8dfdd0d6..ac261b4c 100644
--- a/src/SoapCore.Tests/InvalidXMLTests.cs
+++ b/src/SoapCore.Tests/InvalidXMLTests.cs
@@ -126,6 +126,71 @@ public async Task DuplicatedElement()
 			Assert.IsTrue(body.Contains("<TestResult>a c</TestResult>"));
 		}
 
+		[DataTestMethod]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"Request\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"Request/\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"testRequest/\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"TESTRequest/\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"/\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"https://dos.brianfeucht.com/test/\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"https://dos.brianfeucht.com/test\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"https://dos.brianfeucht.com/TEST\"")]
+		[DataRow("application/soap+xml; charset=utf-8; action=\"https://dos.brianfeucht.com/Test\"")]
+		public async Task InvalidSoapActionContentType(string contentType)
+		{
+			// Arrange
+			var logger = NullLoggerFactory.Instance.CreateLogger<SoapEndpointMiddleware<CustomMessage>>();
+
+			var serviceCollection = new ServiceCollection();
+			serviceCollection.AddSingleton<DuplicatedElementService>();
+			serviceCollection.AddSoapCore();
+
+			var options = new SoapOptions()
+			{
+				Path = "/Service.asmx",
+				EncoderOptions = new[]
+				{
+					new SoapEncoderOptions
+					{
+						MessageVersion = MessageVersion.Soap12WSAddressing10,
+						WriteEncoding = Encoding.UTF8,
+						ReaderQuotas = XmlDictionaryReaderQuotas.Max
+					}
+				},
+				ServiceType = typeof(DuplicatedElementService),
+				SoapModelBounder = new MockModelBounder(),
+				SoapSerializer = SoapSerializer.XmlSerializer
+			};
+
+			var soapCore = new SoapEndpointMiddleware<CustomMessage>(logger, _ => Task.CompletedTask, options);
+
+			var context = new DefaultHttpContext();
+			context.Request.Path = new PathString("/Service.asmx");
+			context.Request.Method = "POST";
+			context.Response.Body = new MemoryStream();
+
+			// Act
+			var request = @"
+<soap12:Envelope xmlns:soap12=""http://www.w3.org/2003/05/soap-envelope"" xmlns:rlx=""https://dos.brianfeucht.com/"">
+    <soap12:Body>
+    <rlx:Test>
+		<eventRef>a</eventRef>
+		<other>c</other>
+    </rlx:Test>
+  </soap12:Body>
+</soap12:Envelope>";
+			context.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(request), false);
+			context.Request.ContentType = contentType;
+
+			await soapCore.Invoke(context, serviceCollection.BuildServiceProvider());
+
+			// Assert
+			context.Response.Body.Seek(0, SeekOrigin.Begin);
+			using var response = new StreamReader(context.Response.Body, Encoding.UTF8);
+			var body = await response.ReadToEndAsync();
+			Assert.IsTrue(body.Contains("<TestResult>a c</TestResult>"));
+		}
+
 		[ServiceContract(Namespace = "https://dos.brianfeucht.com/")]
 		public class DenialOfServiceProofOfConcept
 		{
diff --git a/src/SoapCore/HeadersHelper.cs b/src/SoapCore/HeadersHelper.cs
index 27369d45..0345595a 100644
--- a/src/SoapCore/HeadersHelper.cs
+++ b/src/SoapCore/HeadersHelper.cs
@@ -98,6 +98,12 @@ public static string GetSoapAction(HttpContext httpContext, ref Message message)
 					}
 				}
 
+				if (soapAction != null &&
+				    (string.IsNullOrEmpty(GetTrimmedSoapAction(soapAction)) || string.IsNullOrEmpty(GetTrimmedClearedSoapAction(soapAction))))
+				{
+					soapAction = string.Empty;
+				}
+
 				if (string.IsNullOrEmpty(soapAction))
 				{
 					if (!string.IsNullOrEmpty(message.Headers.Action))
diff --git a/src/SoapCore/SoapEndpointMiddleware.cs b/src/SoapCore/SoapEndpointMiddleware.cs
index bc1ccbbe..db02cdf1 100644
--- a/src/SoapCore/SoapEndpointMiddleware.cs
+++ b/src/SoapCore/SoapEndpointMiddleware.cs
@@ -439,7 +439,11 @@ bool TryGetRequestValue(string key, out StringValues value)
 			context.Response.ContentType = "text/xml";
 
 			var ms = new MemoryStream();
-			XmlWriter writer = XmlWriter.Create(ms, new XmlWriterSettings() { Encoding = DefaultEncodings.UTF8 });
+			XmlWriter writer = XmlWriter.Create(ms, new XmlWriterSettings
+			{
+				Encoding = DefaultEncodings.UTF8,
+
+			});
 			XmlDictionaryWriter dictionaryWriter = XmlDictionaryWriter.CreateDictionaryWriter(writer);
 
 			bodyWriter.WriteBodyContents(dictionaryWriter);
@@ -566,15 +570,15 @@ private async Task<Message> ProcessMessage(Message requestMessage, SoapMessageEn
 
 		private bool TryGetOperation(string methodName, out OperationDescription operation)
 		{
-			operation = _service.Operations.FirstOrDefault(o => o.SoapAction.Equals(methodName, StringComparison.Ordinal)
-							|| o.Name.Equals(HeadersHelper.GetTrimmedSoapAction(methodName), StringComparison.Ordinal)
-							|| methodName.Equals(HeadersHelper.GetTrimmedSoapAction(o.Name), StringComparison.Ordinal));
+			operation = _service.Operations.FirstOrDefault(o => o.SoapAction.Equals(methodName, StringComparison.OrdinalIgnoreCase)
+							|| o.Name.Equals(HeadersHelper.GetTrimmedSoapAction(methodName), StringComparison.OrdinalIgnoreCase)
+							|| methodName.Equals(HeadersHelper.GetTrimmedSoapAction(o.Name), StringComparison.OrdinalIgnoreCase));
 
 			if (operation == null)
 			{
 				operation = _service.Operations.FirstOrDefault(o =>
-							methodName.Equals(HeadersHelper.GetTrimmedClearedSoapAction(o.SoapAction), StringComparison.Ordinal)
-							|| methodName.Contains(HeadersHelper.GetTrimmedSoapAction(o.Name)));
+							methodName.Equals(HeadersHelper.GetTrimmedClearedSoapAction(o.SoapAction), StringComparison.OrdinalIgnoreCase)
+							|| methodName.IndexOf(HeadersHelper.GetTrimmedSoapAction(o.Name), StringComparison.OrdinalIgnoreCase) >= 0);
 			}
 
 			return operation != null;