using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/66035697/using-replace-to-fix-a-long-json-string-doesnt-find-the-given-wod

​

    class TestClass

    {

        public static void Test()

        {

            var json = GetJson();

            Console.WriteLine(json);

            var json2 = json.Replace(",}","},");

            var doc1 = JToken.Parse(json2);

            Console.WriteLine(doc1);

        }   

        static string GetJson()

        {

            return @"[

{properties:[{""property"": ""firstname"", ""value"": ""john"",}{""property"": ""lastname"",""value"": ""smith""}]},

{properties:[{""property"": ""firstname"", ""value"": ""jane"",}{""property"": ""lastname"",""value"": ""doe""}]}

]

";

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​

#if false

`json2 = json.Replace(",}{\"property\"", "},{\"property\"");` works, see https://dotnetfiddle.net/aFMNwO. `Replace(",}","},")` works also, see https://dotnetfiddle.net/Hs3RVg.  By "works" I mean "Can be parsed by Json.NET".  [tag:system.text.json] is more strict and may refuse to parse your JSON even after your fixes.  How are you trying to parse the JSON after fixing it?  Are you sure your large JSON string doesn't have additional errors somewhere?  Maybe there are some [non-printable characters](https://stackoverflow.com/q/3770117/3744182) somewhere in your string, messing up your `Replace`

#endif

​