diff --git a/src/Protocol/Models/FileEvent.cs b/src/Protocol/Models/FileEvent.cs
index 8cc2f5b34..4fd0cc3d7 100644
--- a/src/Protocol/Models/FileEvent.cs
+++ b/src/Protocol/Models/FileEvent.cs
@@ -1,6 +1,7 @@
 using System;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
+using OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters;
 
 namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
 {
@@ -12,7 +13,9 @@ public class FileEvent
         /// <summary>
         ///  The file's URI.
         /// </summary>
+        [JsonConverter(typeof(AbsoluteUriConverter))]
         public Uri Uri { get; set; }
+
         /// <summary>
         ///  The change type.
         /// </summary>
diff --git a/src/Protocol/Models/Location.cs b/src/Protocol/Models/Location.cs
index fc864a04f..defc56498 100644
--- a/src/Protocol/Models/Location.cs
+++ b/src/Protocol/Models/Location.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
+using OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters;
 
 namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
 {
@@ -10,6 +11,7 @@ public class Location : IEquatable<Location>
         /// <summary>
         /// The uri of the document
         /// </summary>
+        [JsonConverter(typeof(AbsoluteUriConverter))]
         public Uri Uri { get; set; }
 
         /// <summary>
diff --git a/src/Protocol/Models/PublishDiagnosticsParams.cs b/src/Protocol/Models/PublishDiagnosticsParams.cs
index 04624f448..b089c7188 100644
--- a/src/Protocol/Models/PublishDiagnosticsParams.cs
+++ b/src/Protocol/Models/PublishDiagnosticsParams.cs
@@ -2,6 +2,7 @@
 using OmniSharp.Extensions.Embedded.MediatR;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
+using OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters;
 
 namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
 {
@@ -10,6 +11,7 @@ public class PublishDiagnosticsParams : IRequest
         /// <summary>
         ///  The URI for which diagnostic information is reported.
         /// </summary>
+        [JsonConverter(typeof(AbsoluteUriConverter))]
         public Uri Uri { get; set; }
 
         /// <summary>
diff --git a/src/Protocol/Models/TextDocumentIdentifier.cs b/src/Protocol/Models/TextDocumentIdentifier.cs
index 702099099..18f99d855 100644
--- a/src/Protocol/Models/TextDocumentIdentifier.cs
+++ b/src/Protocol/Models/TextDocumentIdentifier.cs
@@ -1,6 +1,7 @@
 using System;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
+using OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters;
 
 namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
 {
@@ -15,9 +16,11 @@ public TextDocumentIdentifier(Uri uri)
         {
             Uri = uri;
         }
+
         /// <summary>
         /// The text document's URI.
         /// </summary>
+        [JsonConverter(typeof(AbsoluteUriConverter))]
         public Uri Uri { get; set; }
     }
 }
diff --git a/src/Protocol/Models/WorkspaceFolder.cs b/src/Protocol/Models/WorkspaceFolder.cs
index 50a6f38fb..b83e7433d 100644
--- a/src/Protocol/Models/WorkspaceFolder.cs
+++ b/src/Protocol/Models/WorkspaceFolder.cs
@@ -1,4 +1,6 @@
 using System;
+using Newtonsoft.Json;
+using OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters;
 
 namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
 {
@@ -7,6 +9,7 @@ public class WorkspaceFolder
         /// <summary>
         /// The associated URI for this workspace folder.
         /// </summary>
+        [JsonConverter(typeof(AbsoluteUriConverter))]
         public Uri Uri { get; set; }
 
         /// <summary>
diff --git a/src/Protocol/Serialization/Converters/AbsoluteUriConverter.cs b/src/Protocol/Serialization/Converters/AbsoluteUriConverter.cs
new file mode 100644
index 000000000..b9e9abc87
--- /dev/null
+++ b/src/Protocol/Serialization/Converters/AbsoluteUriConverter.cs
@@ -0,0 +1,57 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information. 	// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+// #see https://github.com/NuGet/NuGet.Server
+using System;
+using Newtonsoft.Json;
+
+namespace OmniSharp.Extensions.LanguageServer.Protocol.Serialization.Converters
+{
+    /// <summary>
+    /// This is necessary because Newtonsoft.Json creates <see cref="Uri"/> instances with
+    /// <see cref="UriKind.RelativeOrAbsolute"/> which treats UNC paths as relative. NuGet.Core uses
+    /// <see cref="UriKind.Absolute"/> which treats UNC paths as absolute. For more details, see:
+    /// https://github.com/JamesNK/Newtonsoft.Json/issues/2128
+    /// </summary>
+    class AbsoluteUriConverter : JsonConverter<Uri>
+    {
+        public override Uri ReadJson(JsonReader reader, Type objectType, Uri existingValue, bool hasExistingValue, JsonSerializer serializer)
+        {
+            if (reader.TokenType == JsonToken.Null)
+            {
+                return null;
+            }
+            else if (reader.TokenType == JsonToken.String)
+            {
+                var uri = new Uri((string)reader.Value, UriKind.RelativeOrAbsolute);
+                if (!uri.IsAbsoluteUri)
+                {
+                    throw new JsonSerializationException($"The Uri must be absolute. Given: {reader.Value}");
+                }
+                return uri;
+            }
+
+            throw new JsonSerializationException("The JSON value must be a string.");
+        }
+
+        public override void WriteJson(JsonWriter writer, Uri value, JsonSerializer serializer)
+        {
+            if (value == null)
+            {
+                writer.WriteNull();
+                return;
+            }
+
+            if (!(value is Uri uriValue))
+            {
+                throw new JsonSerializationException("The value must be a URI.");
+            }
+
+            if (!uriValue.IsAbsoluteUri)
+            {
+                throw new JsonSerializationException("The URI value must be an absolute Uri. Relative URI instances are not allowed.");
+            }
+
+            writer.WriteValue(uriValue.ToString());
+        }
+    }
+}
diff --git a/test/Lsp.Tests/Models/TextDocumentIdentifierTests.cs b/test/Lsp.Tests/Models/TextDocumentIdentifierTests.cs
index 8a2fe60bf..074a0d57f 100644
--- a/test/Lsp.Tests/Models/TextDocumentIdentifierTests.cs
+++ b/test/Lsp.Tests/Models/TextDocumentIdentifierTests.cs
@@ -22,5 +22,41 @@ public void SimpleTest(string expected)
             var deresult = new Serializer(ClientVersion.Lsp3).DeserializeObject<TextDocumentIdentifier>(expected);
             deresult.Should().BeEquivalentTo(model);
         }
+
+        [Fact]
+        public void Should_Fail_To_Serialize_When_Given_A_Non_Relative_Uri()
+        {
+            var serializer = new Serializer(ClientVersion.Lsp3);
+            var model = new TextDocumentIdentifier()
+            {
+                Uri = new Uri("./abc23.cs", UriKind.Relative),
+            };
+
+            Action a = () => serializer.SerializeObject(model);
+            a.Should().Throw<JsonSerializationException>();
+        }
+
+        [Fact]
+        public void Should_Fail_To_Deserialize_When_Given_A_Non_Relative_Uri()
+        {
+            var serializer = new Serializer(ClientVersion.Lsp3);
+            var json = @"{
+                ""uri"":""./0b0jnxg2.kgh.ps1""
+            }";
+
+            Action a = () => serializer.DeserializeObject<TextDocumentIdentifier>(json);
+            a.Should().Throw<JsonSerializationException>();
+        }
+
+        [Fact]
+        public void Should_Deserialize_For_Example_Value()
+        {
+            var serializer = new Serializer(ClientVersion.Lsp3);
+            var result = serializer.DeserializeObject<TextDocumentIdentifier>(@"{
+                ""uri"":""file:///Users/tyler/Code/PowerShell/vscode/PowerShellEditorServices/test/PowerShellEditorServices.Test.E2E/bin/Debug/netcoreapp2.1/0b0jnxg2.kgh.ps1""
+            }");
+
+            result.Uri.Should().Be(new Uri("file:///Users/tyler/Code/PowerShell/vscode/PowerShellEditorServices/test/PowerShellEditorServices.Test.E2E/bin/Debug/netcoreapp2.1/0b0jnxg2.kgh.ps1", UriKind.Absolute));
+        }
     }
 }
diff --git a/test/Lsp.Tests/Models/VersionedTextDocumentIdentifierTests.cs b/test/Lsp.Tests/Models/VersionedTextDocumentIdentifierTests.cs
index 42b617b62..0ca9c66aa 100644
--- a/test/Lsp.Tests/Models/VersionedTextDocumentIdentifierTests.cs
+++ b/test/Lsp.Tests/Models/VersionedTextDocumentIdentifierTests.cs
@@ -14,7 +14,8 @@ public class VersionedTextDocumentIdentifierTests
         [Theory, JsonFixture]
         public void SimpleTest(string expected)
         {
-            var model = new VersionedTextDocumentIdentifier() {
+            var model = new VersionedTextDocumentIdentifier()
+            {
                 Uri = new Uri("file:///abc/123.cs"),
                 Version = 12
             };