Fix Server Error in Application ASP.Net Configura

Server Error in Application , ASP.Net Configuration Error. Windows Server, IIS, App pool,website Server Error in ‘/’ Application. Server Error in '/' Application Web.config ASP.NET Error Handling InvalidOperationException  asp.net object reference not set to an instance of an object Validation of viewstate MAC failed. If this application is hosted by a web farm or cluster, ensure that configuration specifies the same validation Key and validation algorithm. Autogenerate cannot be used in a cluster. viewstate MAC validation Server Error in '/adminflow' Application: A potentially dangerous Request.Form value was detected from the client Server Error in '/' Application. Configuration Error Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. Could not load file or assembly or one of its dependencies. The system cannot find the file specified parser error message: unrecognized attribute targetframework , Source File web.config Line: 145 Fix ASP.Net Configuration Errors in Hosting Server, Migrate Websites, Restore Databases, Configure a Server for .NET Websites, This error can be caused by a virtual directory not being configured as an application in IIS. <system.web><customErrors mode="Off"/></system.web> What We will do: We will fix this issue for your website and make it work perfectly as required. Configure Windows Server and IIS to fix this issue.