elmah

ELMAH (Error Logging Modules and Handlers) is an application-wide error logging facility that is completely pluggable. It can be dynamically added to a running ASP.NET web application, or even all ASP.NET web applications on a machine, without any need for re-compilation or re-deployment. Once ELMAH has been dropped into a running web application and configured appropriately, you get the following facilities without changing a single line of your code: Logging of nearly all unhandled exceptions. A web page to remotely view the entire log of recoded exceptions. A web page to remotely view the full details of any one logged exception, including colored stack traces. In many cases, you can review the original yellow screen of death that ASP.NET generated for a given exception, even with customErrors mode turned off.