diff --git a/src/Kestrel.Core/Adapter/Internal/AdaptedPipeline.cs b/src/Kestrel.Core/Adapter/Internal/AdaptedPipeline.cs
index 2cbb76e5b1..2f44503c0e 100644
--- a/src/Kestrel.Core/Adapter/Internal/AdaptedPipeline.cs
+++ b/src/Kestrel.Core/Adapter/Internal/AdaptedPipeline.cs
@@ -76,9 +76,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
                         {
 #if NETCOREAPP2_1
                             await stream.WriteAsync(buffer.First);
-#else
+#elif NETSTANDARD2_0
                             var array = buffer.First.GetArray();
                             await stream.WriteAsync(array.Array, array.Offset, array.Count);
+#else
+#error TFMs need to be updated
 #endif
                         }
                         else
@@ -87,9 +89,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
                             {
 #if NETCOREAPP2_1
                                 await stream.WriteAsync(memory);
-#else
+#elif NETSTANDARD2_0
                                 var array = memory.GetArray();
                                 await stream.WriteAsync(array.Array, array.Offset, array.Count);
+#else
+#error TFMs need to be updated
 #endif
                             }
                         }
@@ -129,9 +133,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
                     var outputBuffer = Input.Writer.GetMemory(MinAllocBufferSize);
 #if NETCOREAPP2_1
                     var bytesRead = await stream.ReadAsync(outputBuffer);
-#else
+#elif NETSTANDARD2_0
                     var array = outputBuffer.GetArray();
                     var bytesRead = await stream.ReadAsync(array.Array, array.Offset, array.Count);
+#else
+#error TFMs need to be updated
 #endif
                     Input.Writer.Advance(bytesRead);
 
diff --git a/src/Kestrel.Core/Adapter/Internal/LoggingStream.cs b/src/Kestrel.Core/Adapter/Internal/LoggingStream.cs
index f9225b6f48..e591d4acf4 100644
--- a/src/Kestrel.Core/Adapter/Internal/LoggingStream.cs
+++ b/src/Kestrel.Core/Adapter/Internal/LoggingStream.cs
@@ -90,6 +90,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             Log("Read", destination.Slice(0, read));
             return read;
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public async override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
@@ -106,6 +109,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             Log("ReadAsync", destination.Span.Slice(0, read));
             return read;
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override long Seek(long offset, SeekOrigin origin)
@@ -130,6 +136,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             Log("Write", source);
             _inner.Write(source);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
@@ -144,6 +153,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             Log("WriteAsync", source.Span);
             return _inner.WriteAsync(source, cancellationToken);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         private void Log(string method, ReadOnlySpan<byte> buffer)
diff --git a/src/Kestrel.Core/Adapter/Internal/RawStream.cs b/src/Kestrel.Core/Adapter/Internal/RawStream.cs
index 7be7d276f8..4f35b95ebe 100644
--- a/src/Kestrel.Core/Adapter/Internal/RawStream.cs
+++ b/src/Kestrel.Core/Adapter/Internal/RawStream.cs
@@ -74,6 +74,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
         {
             return ReadAsyncInternal(destination);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override void Write(byte[] buffer, int offset, int count)
@@ -97,6 +100,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal
             _output.Write(source.Span);
             await _output.FlushAsync(cancellationToken);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override void Flush()
diff --git a/src/Kestrel.Core/Internal/Http/HttpRequestStream.cs b/src/Kestrel.Core/Internal/Http/HttpRequestStream.cs
index 51b7e7b6cd..ff9c9a9d47 100644
--- a/src/Kestrel.Core/Internal/Http/HttpRequestStream.cs
+++ b/src/Kestrel.Core/Internal/Http/HttpRequestStream.cs
@@ -117,6 +117,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
             return ReadAsyncInternal(destination, cancellationToken);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         private async ValueTask<int> ReadAsyncInternal(Memory<byte> buffer, CancellationToken cancellationToken)
diff --git a/src/Kestrel.Core/Internal/Http/HttpResponseStream.cs b/src/Kestrel.Core/Internal/Http/HttpResponseStream.cs
index aefbe6fb19..0831c74fbf 100644
--- a/src/Kestrel.Core/Internal/Http/HttpResponseStream.cs
+++ b/src/Kestrel.Core/Internal/Http/HttpResponseStream.cs
@@ -118,6 +118,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
             return new ValueTask(_httpResponseControl.WriteAsync(source, cancellationToken));
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public void StartAcceptingWrites()
diff --git a/src/Kestrel.Core/Internal/Http/HttpUpgradeStream.cs b/src/Kestrel.Core/Internal/Http/HttpUpgradeStream.cs
index d6fedc0518..0b89d00ed1 100644
--- a/src/Kestrel.Core/Internal/Http/HttpUpgradeStream.cs
+++ b/src/Kestrel.Core/Internal/Http/HttpUpgradeStream.cs
@@ -150,6 +150,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         {
             return _requestStream.ReadAsync(destination, cancellationToken);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override Task CopyToAsync(Stream destination, int bufferSize, CancellationToken cancellationToken)
@@ -167,6 +170,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         {
             return _responseStream.WriteAsync(source, cancellationToken);
         }
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override long Seek(long offset, SeekOrigin origin)
diff --git a/src/Kestrel.Core/Internal/Http/MessageBody.cs b/src/Kestrel.Core/Internal/Http/MessageBody.cs
index d96aa99d47..339c9d182a 100644
--- a/src/Kestrel.Core/Internal/Http/MessageBody.cs
+++ b/src/Kestrel.Core/Internal/Http/MessageBody.cs
@@ -90,9 +90,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                             // - We change the Kestrel Memory Pool to not use pinned arrays but instead use native memory
 #if NETCOREAPP2_1
                             await destination.WriteAsync(memory);
-#else
+#elif NETSTANDARD2_0
                             var array = memory.GetArray();
                             await destination.WriteAsync(array.Array, array.Offset, array.Count, cancellationToken);
+#else
+#error TFMs need to be updated
 #endif
                         }
                     }
diff --git a/src/Kestrel.Core/Internal/HttpsConnectionAdapter.cs b/src/Kestrel.Core/Internal/HttpsConnectionAdapter.cs
index 95ee435b43..4058635e68 100644
--- a/src/Kestrel.Core/Internal/HttpsConnectionAdapter.cs
+++ b/src/Kestrel.Core/Internal/HttpsConnectionAdapter.cs
@@ -166,7 +166,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Https.Internal
                 }
 
                 await sslStream.AuthenticateAsServerAsync(sslOptions, CancellationToken.None);
-#else
+#elif NETSTANDARD2_0 // No ALPN support
                 var serverCert = _serverCertificate;
                 if (_serverCertificateSelector != null)
                 {
@@ -179,6 +179,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Https.Internal
                 }
                 await sslStream.AuthenticateAsServerAsync(serverCert, certificateRequired,
                         _options.SslProtocols, _options.CheckCertificateRevocation);
+#else
+#error TFMs need to be updated
 #endif
             }
             catch (OperationCanceledException)
@@ -201,6 +203,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Https.Internal
 #if NETCOREAPP2_1
             feature.ApplicationProtocol = sslStream.NegotiatedApplicationProtocol.Protocol;
             context.Features.Set<ITlsApplicationProtocolFeature>(feature);
+#elif NETSTANDARD2_0 // No ALPN support
+#else
+#error TFMs need to be updated
 #endif
             feature.ClientCertificate = ConvertToX509Certificate2(sslStream.RemoteCertificate);
 
diff --git a/src/Kestrel.Core/Internal/Infrastructure/WrappingStream.cs b/src/Kestrel.Core/Internal/Infrastructure/WrappingStream.cs
index 9485392825..0be1c97d7e 100644
--- a/src/Kestrel.Core/Internal/Infrastructure/WrappingStream.cs
+++ b/src/Kestrel.Core/Internal/Infrastructure/WrappingStream.cs
@@ -71,6 +71,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 #if NETCOREAPP2_1
         public override ValueTask<int> ReadAsync(Memory<byte> destination, CancellationToken cancellationToken = default)
             => _inner.ReadAsync(destination, cancellationToken);
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override int ReadByte()
@@ -91,6 +94,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 #if NETCOREAPP2_1
         public override ValueTask WriteAsync(ReadOnlyMemory<byte> source, CancellationToken cancellationToken = default)
             => _inner.WriteAsync(source, cancellationToken);
+#elif NETSTANDARD2_0
+#else
+#error TFMs need to be updated
 #endif
 
         public override void WriteByte(byte value)
diff --git a/src/Kestrel.Transport.Sockets/Internal/SocketReceiver.cs b/src/Kestrel.Transport.Sockets/Internal/SocketReceiver.cs
index 2116c03cd5..223d5e9b70 100644
--- a/src/Kestrel.Transport.Sockets/Internal/SocketReceiver.cs
+++ b/src/Kestrel.Transport.Sockets/Internal/SocketReceiver.cs
@@ -25,10 +25,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.Internal
         {
 #if NETCOREAPP2_1
             _eventArgs.SetBuffer(buffer);
-#else
+#elif NETSTANDARD2_0
             var segment = buffer.GetArray();
 
             _eventArgs.SetBuffer(segment.Array, segment.Offset, segment.Count);
+#else
+#error TFMs need to be updated
 #endif
             if (!_socket.ReceiveAsync(_eventArgs))
             {
diff --git a/src/Kestrel.Transport.Sockets/Internal/SocketSender.cs b/src/Kestrel.Transport.Sockets/Internal/SocketSender.cs
index 26e22b664d..0684560d87 100644
--- a/src/Kestrel.Transport.Sockets/Internal/SocketSender.cs
+++ b/src/Kestrel.Transport.Sockets/Internal/SocketSender.cs
@@ -36,8 +36,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.Internal
 
 #if NETCOREAPP2_1
             if (!_eventArgs.MemoryBuffer.Equals(Memory<byte>.Empty))
-#else
+#elif NETSTANDARD2_0
             if (_eventArgs.Buffer != null)
+#else
+#error TFMs need to be updated
 #endif
             {
                 _eventArgs.SetBuffer(null, 0, 0);
@@ -63,10 +65,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.Internal
 
 #if NETCOREAPP2_1
             _eventArgs.SetBuffer(MemoryMarshal.AsMemory(memory));
-#else
+#elif NETSTANDARD2_0
             var segment = memory.GetArray();
 
             _eventArgs.SetBuffer(segment.Array, segment.Offset, segment.Count);
+#else
+#error TFMs need to be updated
 #endif
             if (!_socket.SendAsync(_eventArgs))
             {
diff --git a/test/Kestrel.FunctionalTests/HttpsConnectionAdapterTests.cs b/test/Kestrel.FunctionalTests/HttpsConnectionAdapterTests.cs
index 6f7b55a3a2..7798820b10 100644
--- a/test/Kestrel.FunctionalTests/HttpsConnectionAdapterTests.cs
+++ b/test/Kestrel.FunctionalTests/HttpsConnectionAdapterTests.cs
@@ -154,8 +154,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
                             Assert.NotNull(connection.Features.Get<SslStream>());
 #if NETCOREAPP2_2
                             Assert.Equal("localhost", name);
-#else
+#elif NET461
                             Assert.Null(name);
+#else
+#error TFMs need to be updated
 #endif
                             selectorCalled++;
                             return _x509Certificate2;
@@ -194,8 +196,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
                             Assert.NotNull(connection.Features.Get<SslStream>());
 #if NETCOREAPP2_2
                             Assert.Equal("localhost", name);
-#else
+#elif NET461
                             Assert.Null(name);
+#else
+#error TFMs need to be updated
 #endif
                             selectorCalled++;
                             if (selectorCalled == 1)
@@ -282,8 +286,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
                             Assert.NotNull(connection.Features.Get<SslStream>());
 #if NETCOREAPP2_2
                             Assert.Equal("localhost", name);
-#else
+#elif NET461
                             Assert.Null(name);
+#else
+#error TFMs need to be updated
 #endif
                             selectorCalled++;
                             return _x509Certificate2;
diff --git a/test/shared/PassThroughConnectionAdapter.cs b/test/shared/PassThroughConnectionAdapter.cs
index cfad5c7e7c..351a2c9e93 100644
--- a/test/shared/PassThroughConnectionAdapter.cs
+++ b/test/shared/PassThroughConnectionAdapter.cs
@@ -140,7 +140,7 @@ namespace Microsoft.AspNetCore.Testing
                 _innerStream.Close();
             }
 
-#if NETCOREAPP2_1
+#if NETCOREAPP2_2
             public override int Read(Span<byte> buffer)
             {
                 return _innerStream.Read(buffer);
@@ -165,7 +165,10 @@ namespace Microsoft.AspNetCore.Testing
             {
                 _innerStream.CopyTo(destination, bufferSize);
             }
-#endif 
+#elif NET461
+#else
+#error TFMs need to be updated
+#endif
         }
     }
 }
diff --git a/test/shared/TestApplicationErrorLogger.cs b/test/shared/TestApplicationErrorLogger.cs
index 2f05ec174c..bff77f8efa 100644
--- a/test/shared/TestApplicationErrorLogger.cs
+++ b/test/shared/TestApplicationErrorLogger.cs
@@ -45,9 +45,8 @@ namespace Microsoft.AspNetCore.Testing
         public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
         {
             var exceptionIsIgnored = IgnoredExceptions.Contains(exception?.GetType());
-#if true
+
             if (logLevel == LogLevel.Critical && ThrowOnCriticalErrors && !exceptionIsIgnored)
-#endif
             {
                 var log = $"Log {logLevel}[{eventId}]: {formatter(state, exception)} {exception}";