How can I include SessionID in log files using log4net in ASP.NET?
Alexander K. is nearly correct. The only problem with it is that the PostAcquireRequestState event also occurs for static requests. A call to Session in this situation will cause a HttpException.
Therefore the correct solution becomes:
protected void Application_PostAcquireRequestState(object sender, EventArgs e){ if (Context.Handler is IRequiresSessionState) { log4net.ThreadContext.Properties["SessionId"] = Session.SessionID; }}
UPDATE (2014-06-12): Starting from log4net 1.2.11 you can use %aspnet-request{ASP.NET_SessionId} in conversion pattern for this purpose.
References:https://issues.apache.org/jira/browse/LOG4NET-87http://logging.apache.org/log4net/release/sdk/log4net.Layout.PatternLayout.html
You should create Application_PostAcquireRequestState handler in Global.asax.cs (it is called in every request):
protected void Application_PostAcquireRequestState(object sender, EventArgs e){ log4net.ThreadContext.Properties["SessionID"] = Session.SessionID;}And add [%property{SessionID}] to conversionPattern.