diff --git a/Build/build.ps1 b/Build/build.ps1
index db07034f..f17ab5a2 100644
--- a/Build/build.ps1
+++ b/Build/build.ps1
@@ -30,7 +30,7 @@
   $nunitConsolePath = "$buildDir\Temp\NUnit.ConsoleRunner.$nunitConsoleVersion"
 
   $builds = @(
-    @{Framework = "netstandard2.0"; TestsFunction = "NetCliTests"; TestFramework = "netcoreapp2.0"; Enabled=$true},
+    @{Framework = "netstandard2.0"; TestsFunction = "NetCliTests"; TestFramework = "netcoreapp2.1"; Enabled=$true},
     @{Framework = "netstandard1.3"; TestsFunction = "NetCliTests"; TestFramework = "netcoreapp1.1"; Enabled=$true},
     @{Framework = "netstandard1.0"; TestsFunction = "NetCliTests"; TestFramework = "netcoreapp1.0"; Enabled=$true},
     @{Framework = "net45"; TestsFunction = "NUnitTests"; TestFramework = "net46"; NUnitFramework="net-4.0"; Enabled=$true},
diff --git a/Src/Newtonsoft.Json.Tests/Issues/Issue1517.cs b/Src/Newtonsoft.Json.Tests/Issues/Issue1517.cs
deleted file mode 100644
index c801b23a..00000000
--- a/Src/Newtonsoft.Json.Tests/Issues/Issue1517.cs
+++ /dev/null
@@ -1,79 +0,0 @@
-#region License
-// Copyright (c) 2007 James Newton-King
-//
-// Permission is hereby granted, free of charge, to any person
-// obtaining a copy of this software and associated documentation
-// files (the "Software"), to deal in the Software without
-// restriction, including without limitation the rights to use,
-// copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the
-// Software is furnished to do so, subject to the following
-// conditions:
-//
-// The above copyright notice and this permission notice shall be
-// included in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
-// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
-// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
-// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-// OTHER DEALINGS IN THE SOFTWARE.
-#endregion
-
-#if (NETSTANDARD2_0)
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Globalization;
-using System.IO;
-using System.Linq;
-using System.Security.Cryptography;
-using System.Text;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-using System.Xml;
-using Newtonsoft.Json.Serialization;
-#if !NET20
-using System.Xml.Linq;
-#endif
-#if DNXCORE50
-using Xunit;
-using Test = Xunit.FactAttribute;
-using Assert = Newtonsoft.Json.Tests.XUnitAssert;
-#else
-using NUnit.Framework;
-#endif
-
-namespace Newtonsoft.Json.Tests.Issues
-{
-    [TestFixture]
-    public class Issue1517 : TestFixtureBase
-    {
-        [Test]
-        public void Test()
-        {
-            RSAParameters rsaParameters = new RSAParameters();
-            rsaParameters.D = new byte[] { 1, 2 };
-            rsaParameters.DP = new byte[] { 2, 4 };
-            rsaParameters.DQ = new byte[] { 5, 6 };
-            rsaParameters.Exponent = new byte[] { 7, 8 };
-            rsaParameters.InverseQ = new byte[] { 9, 10 };
-            rsaParameters.Modulus = new byte[] { 11, 12 };
-            rsaParameters.P = new byte[] { 13, 14 };
-            rsaParameters.Q = new byte[] { 15, 16 };
-
-            string json = JsonConvert.SerializeObject(rsaParameters, Formatting.Indented);
-
-            // a subset of values is serialized because of the NotSerializedAttribute
-            // https://msdn.microsoft.com/en-us/library/system.security.cryptography.rsaparameters.d(v=vs.110).aspx
-            StringAssert.AreEqual(@"{
-  ""Exponent"": ""Bwg="",
-  ""Modulus"": ""Cww=""
-}", json);
-        }
-    }
-}
-#endif
\ No newline at end of file
diff --git a/Src/Newtonsoft.Json.Tests/Issues/Issue1757.cs b/Src/Newtonsoft.Json.Tests/Issues/Issue1757.cs
new file mode 100644
index 00000000..83704f5a
--- /dev/null
+++ b/Src/Newtonsoft.Json.Tests/Issues/Issue1757.cs
@@ -0,0 +1,117 @@
+#region License
+// Copyright (c) 2007 James Newton-King
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+#endregion
+
+#if (NETSTANDARD2_0)
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Reflection.Emit;
+using System.Runtime.Serialization;
+#if !(NET20 || NET35 || NET40 || PORTABLE40)
+using System.Threading.Tasks;
+#endif
+using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Linq;
+using Newtonsoft.Json.Serialization;
+using Newtonsoft.Json.Utilities;
+#if DNXCORE50
+using Xunit;
+using Test = Xunit.FactAttribute;
+using Assert = Newtonsoft.Json.Tests.XUnitAssert;
+using System.Text;
+#else
+using NUnit.Framework;
+#endif
+
+namespace Newtonsoft.Json.Tests.Issues
+{
+    [TestFixture]
+    public class Issue1757 : TestFixtureBase
+    {
+        [Test]
+        public void Test_Serialize()
+        {
+            JsonConvert.SerializeObject(new TestObject());
+        }
+
+        [Test]
+        public void Test_SerializeEncoding()
+        {
+            JsonConvert.SerializeObject(Encoding.UTF8);
+        }
+
+        [Test]
+        public void Test_Deserialize()
+        {
+            JsonConvert.DeserializeObject<TestObject>(@"{'Room':{},'RefLike':{}}");
+        }
+
+        public class TestObject
+        {
+            public Span<int> this[int i]
+            {
+                get { return default(Span<int>); }
+                set { DoNothing(value); }
+            }
+            public static Span<int> Space
+            {
+                get { return default(Span<int>); }
+                set { DoNothing(value); }
+            }
+            public Span<int> Room
+            {
+                get { return default(Span<int>); }
+                set { DoNothing(value); }
+            }
+            public MyByRefLikeType RefLike
+            {
+                get { return default(MyByRefLikeType); }
+                set { }
+            }
+            private static void DoNothing(Span<int> param)
+            {
+                throw new InvalidOperationException("Should never be called.");
+            }
+            public string PrintMySpan(string str, Span<int> mySpan = default)
+            {
+                return str;
+            }
+
+            public Span<int> GetSpan(int[] array)
+            {
+                return array.AsSpan();
+            }
+        }
+
+        public ref struct MyByRefLikeType
+        {
+            public MyByRefLikeType(int i) { }
+            public static int Index;
+        }
+    }
+}
+#endif
\ No newline at end of file
diff --git a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.csproj b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.csproj
index d6f88865..752d33ac 100644
--- a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.csproj
+++ b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks Condition="'$(TestFrameworks)'==''">net46;net451;net452;net40;net35;net20;netcoreapp2.0;netcoreapp1.1;netcoreapp1.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(TestFrameworks)'==''">net46;net451;net452;net40;net35;net20;netcoreapp2.1;netcoreapp1.1;netcoreapp1.0</TargetFrameworks>
     <TargetFrameworks Condition="'$(TestFrameworks)'!=''">$(TestFrameworks)</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <VersionPrefix>1.0</VersionPrefix>
@@ -13,7 +13,7 @@
     <RootNamespace>Newtonsoft.Json.Tests</RootNamespace>
     <IsPackable>false</IsPackable>
     <!-- Workaround for https://github.com/nunit/nunit3-vs-adapter/issues/296 -->
-    <DebugType Condition="'$(TargetFramework)' != '' AND '$(TargetFramework)' != 'netcoreapp1.0' AND '$(TargetFramework)' != 'netcoreapp1.1' AND '$(TargetFramework)' != 'netcoreapp2.0'">Full</DebugType>    
+    <DebugType Condition="'$(TargetFramework)' != '' AND '$(TargetFramework)' != 'netcoreapp1.0' AND '$(TargetFramework)' != 'netcoreapp1.1' AND '$(TargetFramework)' != 'netcoreapp2.1'">Full</DebugType>    
     <!-- Disabled because SourceLink isn't referenced to calculate paths -->
     <DeterministicSourcePaths>false</DeterministicSourcePaths>
   </PropertyGroup>
@@ -153,7 +153,7 @@
     <DefineConstants>NET20;$(AdditionalConstants)</DefineConstants>
   </PropertyGroup>
 
-  <ItemGroup Condition="'$(TargetFramework)'=='netcoreapp2.0'">
+  <ItemGroup Condition="'$(TargetFramework)'=='netcoreapp2.1'">
     <PackageReference Include="BenchmarkDotNet" Version="0.10.10" />
     <PackageReference Include="FSharp.Core" Version="4.2.3" />
     <PackageReference Include="System.ObjectModel" Version="4.3.0" />
@@ -168,7 +168,7 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.2" />
   </ItemGroup>
-  <PropertyGroup Condition="'$(TargetFramework)'=='netcoreapp2.0'">
+  <PropertyGroup Condition="'$(TargetFramework)'=='netcoreapp2.1'">
     <AssemblyTitle>Json.NET Tests .NET Standard 2.0</AssemblyTitle>
     <ReferringTargetFrameworkForProjectReferences>.NETStandard,Version=v2.0</ReferringTargetFrameworkForProjectReferences>
     <DefineConstants>NETSTANDARD2_0;DNXCORE50;PORTABLE;HAVE_BENCHMARKS;$(AdditionalConstants)</DefineConstants>
diff --git a/Src/Newtonsoft.Json.Tests/Serialization/SerializationErrorHandlingTests.cs b/Src/Newtonsoft.Json.Tests/Serialization/SerializationErrorHandlingTests.cs
index ee3be244..6f2b5f17 100644
--- a/Src/Newtonsoft.Json.Tests/Serialization/SerializationErrorHandlingTests.cs
+++ b/Src/Newtonsoft.Json.Tests/Serialization/SerializationErrorHandlingTests.cs
@@ -390,7 +390,8 @@ namespace Newtonsoft.Json.Tests.Serialization
             {
 #if !(NET20 || NET35)
                 "[1] - 1 - The string was not recognized as a valid DateTime. There is an unknown word starting at index 0.",
-                "[1] - 1 - String was not recognized as a valid DateTime."
+                "[1] - 1 - String was not recognized as a valid DateTime.",
+                "[1] - 1 - The string 'I am not a date and will error!' was not recognized as a valid DateTime. There is an unknown word starting at index '0'."
 #else
     // handle typo fix in later versions of .NET
                 "[1] - 1 - The string was not recognized as a valid DateTime. There is an unknown word starting at index 0.",
diff --git a/Src/Newtonsoft.Json/Serialization/DefaultContractResolver.cs b/Src/Newtonsoft.Json/Serialization/DefaultContractResolver.cs
index 44309c65..e3fa24e2 100644
--- a/Src/Newtonsoft.Json/Serialization/DefaultContractResolver.cs
+++ b/Src/Newtonsoft.Json/Serialization/DefaultContractResolver.cs
@@ -198,6 +198,25 @@ namespace Newtonsoft.Json.Serialization
             return _contractCache.Get(type);
         }
 
+        private static bool FilterMembers(MemberInfo member)
+        {
+            if (member is PropertyInfo property)
+            {
+                if (ReflectionUtils.IsIndexedProperty(property))
+                {
+                    return false;
+                }
+
+                return !ReflectionUtils.IsByRefLikeType(property.PropertyType);
+            }
+            else if (member is FieldInfo field)
+            {
+                return !ReflectionUtils.IsByRefLikeType(field.FieldType);
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// Gets the serializable members for the type.
         /// </summary>
@@ -215,7 +234,7 @@ namespace Newtonsoft.Json.Serialization
             MemberSerialization memberSerialization = JsonTypeReflector.GetObjectMemberSerialization(objectType, ignoreSerializableAttribute);
 
             IEnumerable<MemberInfo> allMembers = ReflectionUtils.GetFieldsAndProperties(objectType, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static)
-                .Where(m => !ReflectionUtils.IsIndexedProperty(m));
+                .Where(FilterMembers);
 
             List<MemberInfo> serializableMembers = new List<MemberInfo>();
 
@@ -227,7 +246,7 @@ namespace Newtonsoft.Json.Serialization
 
 #pragma warning disable 618
                 List<MemberInfo> defaultMembers = ReflectionUtils.GetFieldsAndProperties(objectType, DefaultMembersSearchFlags)
-                    .Where(m => !ReflectionUtils.IsIndexedProperty(m)).ToList();
+                    .Where(FilterMembers).ToList();
 #pragma warning restore 618
 
                 foreach (MemberInfo member in allMembers)
diff --git a/Src/Newtonsoft.Json/Utilities/ReflectionUtils.cs b/Src/Newtonsoft.Json/Utilities/ReflectionUtils.cs
index 056d55e5..5f8741a5 100644
--- a/Src/Newtonsoft.Json/Utilities/ReflectionUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/ReflectionUtils.cs
@@ -457,25 +457,24 @@ namespace Newtonsoft.Json.Utilities
             }
         }
 
-        /// <summary>
-        /// Determines whether the member is an indexed property.
-        /// </summary>
-        /// <param name="member">The member.</param>
-        /// <returns>
-        /// 	<c>true</c> if the member is an indexed property; otherwise, <c>false</c>.
-        /// </returns>
-        public static bool IsIndexedProperty(MemberInfo member)
+        public static bool IsByRefLikeType(Type type)
         {
-            ValidationUtils.ArgumentNotNull(member, nameof(member));
-
-            if (member is PropertyInfo propertyInfo)
-            {
-                return IsIndexedProperty(propertyInfo);
-            }
-            else
+            if (!type.IsValueType())
             {
                 return false;
             }
+
+            // IsByRefLike flag on type is not available in netstandard2.0
+            Attribute[] attributes = GetAttributes(type, null, false);
+            for (int i = 0; i < attributes.Length; i++)
+            {
+                if (string.Equals(attributes[i].GetType().FullName, "System.Runtime.CompilerServices.IsByRefLikeAttribute", StringComparison.Ordinal))
+                {
+                    return true;
+                }
+            }
+
+            return false;
         }
 
         /// <summary>