Exception Filter in MVC

## 1. Install log4net using NuGet

## 2. Add assembly in AssemblyInfo.cs file
[assembly: log4net.Config.XmlConfigurator(ConfigFile = "Web.config", Watch = true)]

## 3. Add settings in web.config
<configuration>
  <configSections>
    :::
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net" />
  </configSections>
  :::
  <log4net>
    <appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
      <file value="Logs/LogFile.txt" />
      <appendToFile value="true" />
      <maximumFileSize value="500KB" />
      <maxSizeRollBackups value="2" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date %level %logger - %message%newline" />
      </layout>
    </appender>
    <root>
      <level value="All" />
      <appender-ref ref="RollingFile" />
    </root>
  </log4net>
</configuration>

## 4. Create CustomExceptionFilter.cs inside Filters folder on root
    public class CustomExceptionFilter : HandleErrorAttribute
    {
        public override void OnException(ExceptionContext filterContext)
        {
            //if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
            //{
            //    return;
            //}

            //if (new HttpException(null, filterContext.Exception).GetHttpCode() != 500)
            //{
            //    return;
            //}

            //if (!ExceptionType.IsInstanceOfType(filterContext.Exception))
            //{
            //    return;
            //}

            // if the request is AJAX return JSON else view.
            if (filterContext.HttpContext.Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                filterContext.Result = new JsonResult
                {
                    JsonRequestBehavior = JsonRequestBehavior.AllowGet,
                    Data = new
                    {
                        error = true,
                        message = filterContext.Exception.Message
                    }
                };
            }
            else
            {
                var controllerName = (string)filterContext.RouteData.Values["controller"];
                var actionName = (string)filterContext.RouteData.Values["action"];
                var model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);

                filterContext.Result = new ViewResult
                {
                    ViewName = View,
                    MasterName = Master,
                    ViewData = new ViewDataDictionary(model),
                    TempData = filterContext.Controller.TempData
                };
            }

            log4net.ILog log = log4net.LogManager.GetLogger(filterContext.RouteData.Values["controller"].ToString());

            var msg = filterContext.Exception.Message;
            var ex = filterContext.Exception;

            log.Error(ex.ToString() + " | " + msg);

            filterContext.ExceptionHandled = true;
            filterContext.HttpContext.Response.Clear();
            filterContext.HttpContext.Response.StatusCode = 500;

            filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
        }
    }
    
## 5. Register filter globally
    public class FilterConfig
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            ::::::::::::::::
            filters.Add(new CustomExceptionFilter());
        }
    }
    
## 6. Create Logs folder on root of the project