Log4net rolling daily filename with date in the file name

In your Log4net config file, use the following parameter with the RollingFileAppender:

<param name="DatePattern" value="dd.MM.yyyy'.log'" />

For a RollingLogFileAppender you also need these elements and values:

<rollingStyle value="Date" />
<staticLogFileName value="false" />

The extended configuration section in a previous response with

 ...
 ...
 <rollingStyle value="Composite" />
 ...
 ...

listed works but I did not have to use

<staticLogFileName value="false" /> 

. I think the RollingAppender must (logically) ignore that setting since by definition the file gets rebuilt each day when the application restarts/reused. Perhaps it does matter for immediate rollover EVERY time the application starts.

I moved configuration to code to enable easy modification from CI using system variable. I used this code for file name and result is 'Log_03-23-2020.log'

            log4net.Repository.ILoggerRepository repository = LogManager.GetRepository(Assembly.GetEntryAssembly());
            Hierarchy hierarchy = (Hierarchy)repository;
            PatternLayout patternLayout = new PatternLayout();
            patternLayout.ConversionPattern = "%date %level - %message%newline%exception";
            patternLayout.ActivateOptions();

            RollingFileAppender roller = new RollingFileAppender();
            roller.AppendToFile = true;
            roller.File = "Log_";
            roller.DatePattern = "MM-dd-yyyy'.log'";
            roller.Layout = patternLayout;
            roller.MaxFileSize = 1024*1024*10;
            roller.MaxSizeRollBackups = 10;
            roller.StaticLogFileName = false;
            roller.RollingStyle = RollingFileAppender.RollingMode.Composite;
            roller.ActivateOptions();
            hierarchy.Root.AddAppender(roller);