Just a quick note on getting log4net 1.2.10 working with ASP.Net 4. I had been working with log4net version 1.2.10.0 in ASP.Net 3.5 and it had been working but after upgrading the project to ASP.NET 4 I noticed an odd behavior. It would log only one message to the log file and refused to log any further messages until the application was restarted.