log4net: Error on loading custom appender

Question

I extended AppenderSkeleton to create a custom appender called HTTPAppender, but something is up with the reference to it in the xml file. Log4Net is clearly unable to find my custom appender. Is there a way to reference it from the xml file to point to my project, or would I have to add my custom appender's source code to log4net's so it's packaged in log4net.dll?

I get the following error in the Immediate window when debugging:

log4net:ERROR XmlHierarchyConfigurator: Could not create Appender [HTTPAppender] of type [HTTPAppender.HTTPAppender,HTTPAppender]. Reported error follows.
System.IO.FileNotFoundException: Could not load file or assembly 'HTTPAppender' or one of its dependencies. The system cannot find the file specified.
File name: 'HTTPAppender'
   at System.RuntimeTypeHandle._GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName)
   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
...etc

Here's the log4net section of the xml file:

<log4net> <appender name="HTTPAppender" type="HTTPAppender.HTTPAppender,HTTPAppender"> <evaluator type="log4net.Core.LevelEvaluator,log4net"> <threshold value="WARN"/> </evaluator> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="#%level - %message" /> </layout> </appender> <root> <level value="ALL" /> <appender-ref ref="HTTPAppender" /> </root> <logger name="log4netErrorLog" > <level value="DEBUG" /> <appender-ref ref="HTTPAppender" /> </logger> </log4net>

Answer 1

I would assume that the assembly cannot be found. Is the name of the assembly indeed 'HTTPAppender' and is it in the same path as the calling assembly?

Answer 2

I've had the same issue. If your custom appender project uses a certain log4net.dll, and your project that's going to use your custom appender uses a different log4net.dll, it will not be able to find it.

Answer 3

I was also stuck in that issue finally I fixed it.

The solution is HTTPAppender class should have a Default contructor.

I am confident about that this error "Could not create Appender" is come because doesn't have default constructor

Answer 4

i think this will help you

http://weblogs.asp.net/tgraham/archive/2007/05/02/loading-the-assembly-for-a-custom-log4net-appender.aspx

Answer 5

I run into the same issue recently. I fixed it by adding the assembly name after the fully qualified name of the type with a comma in the type attribute. Please see below.

<log4net>
    <appender name="LogFileAppender" type="TestHarness.Model.CustomRollingFileAppender, TestHarness.Model">
 </log4net>

Answer 6

If you are using any non standard assemblies, put them in the application directory together with your assembly. If that doesn't help, try giving your assembly a strong name and using the full name in the log4net config file. you can also try putting it into GAC.