Upgrade .NET Framework version in all projects at once

UpgradeFrameworkInProjects.cs

using System;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

namespace UpgradeFrameworkInProjects
{
	class Program
	{
		private const string exitCode = "0";
		private const string defaultFolderPath = @"C:\Solutions\MySolution";
		private const string defaultFrameworkVersion = "v4.6.1";

		static void Main(string[] args)
		{
			while (UpgradeFrameworkInProjects())
			{
				Console.WriteLine();
				Console.WriteLine();

				Console.WriteLine("Press any key to restart.");
				Console.WriteLine($"Type {exitCode} to exit the program.");
				Console.ReadKey();
			}
		}

		private static bool UpgradeFrameworkInProjects()
		{
			Console.WriteLine("---");
			Console.WriteLine("This program updates .NET Framework version in all projects in a solution.\n");
			
			Console.WriteLine($"Hit enter to run in this solution: {defaultFolderPath}");
			Console.Write("Or enter path to solution folder: ");
			string folderPath = Console.ReadLine().Trim();

			if (string.IsNullOrWhiteSpace(folderPath))
				folderPath = defaultFolderPath;
			else if (folderPath == exitCode)
				return false;

			Console.WriteLine($"Hit enter to update projects to version: {defaultFrameworkVersion}");
			Console.Write("Or enter the version: v");
			string newVersion = Console.ReadLine().Trim();

			if (string.IsNullOrWhiteSpace(newVersion))
				newVersion = defaultFrameworkVersion;
			else if (newVersion == exitCode)
				return false;

			if (newVersion.ToLower().StartsWith("v"))
				newVersion = newVersion.Remove(0, 1);

			int count = 0;
			try
			{
				string[] files = Directory.GetFiles(folderPath, "*.csproj", SearchOption.AllDirectories);
				foreach (var file in files)
				{

					string text = File.ReadAllText(file);
					string pattern = @"<\s*TargetFrameworkVersion\s*>v([\d\.]+)<\/\s*TargetFrameworkVersion\s*>";
					text = Regex.Replace(text, pattern, $"<TargetFrameworkVersion>v{newVersion}</TargetFrameworkVersion>");

					File.WriteAllText(file, text);
					Console.WriteLine($"{++count}. Updated {file.Split('\\').LastOrDefault()}");
				}
			}
			catch (Exception exception)
			{
				Console.WriteLine($"Error: {exception.Message}");
			}

			Console.WriteLine();
			Console.WriteLine($"Updated Framework version in {count} projects.");

			return true;
		}