NLog Exception when parsing nlog.config - Target c

Question

I'm developing a C# .NET Core 2.2 Web-Api on Visual Studio 2017. I implement NLog 4.6.1 like described on github. When I start my application using IIS NLog does not write into the Elasticsearch. A error occurs at the line at program.cs

var logger = NLog.Web.NLogBuilder.ConfigureNLog("NLog.config").GetCurrentClassLogger();

I find a error message at NLogError.log:

2019-06-12 09:00:49.1606 Error Penter code herearsing configuration from NLog.config failed. Exception: NLog.NLogConfigurationException: Exception when parsing NLog.config.  ---> System.ArgumentException: Target cannot be found: 'EventLog'
   at NLog.Config.Factory`2.CreateInstance(String itemName)
   at NLog.Config.LoggingConfigurationParser.ParseTargetsElement(ILoggingConfigurationElement targetsElement)
   at NLog.Config.LoggingConfigurationParser.ParseNLogSection(ILoggingConfigurationElement configSection)
   at NLog.Config.LoggingConfigurationParser.LoadConfig(ILoggingConfigurationElement nlogConfig, String basePath)
   at NLog.Config.XmlLoggingConfiguration.ParseNLogElement(ILoggingConfigurationElement nlogElement, String filePath, Boolean autoReloadDefault)
   at NLog.Config.XmlLoggingConfiguration.Initialize(XmlReader reader, String fileName, Boolean ignoreErrors)
   --- End of inner exception stack trace ---

I tried to shorten my config file to avoid other problems but still same error. The target "EventLog" is to find there.

NLog.config:

<?xml version="1.0" encoding="utf-8" ?>
      <nlog autoReload="true" throwExceptions="false"
          internalLogLevel="Error" internalLogFile="NLogError.log"
          xmlns="http://www.nlog-project.org/schemas/NLog.xsd" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
          <targets>
            <target name="EventLog" xsi:type="EventLog"
              layout="${longdate} ${level} ${callsite} -> ${message} 
              ${exception:format=Message,StackTrace}"
              source="MonDBSvc" />
          </targets>
          <rules>
            <logger name="MonDbSvc" minlevel="Error" writeTo="EventLog" 
              log="Application" />
          </rules>
      </nlog>

The NLog.config file and the program.cs file are on the same root level at the application folder.

I tried writing NLog.config nad nlog.config for the filename and at this code line above.

What could cause this parsing problem? What could I try to fix it?

Thanks for support!

When I change the log level from error to warn I get a more explicit message. I'm quit shure that the xml is valid as a xml.

2019-06-12 10:27:51.3735 Info Message Template Auto Format enabled
2019-06-12 10:27:51.4347 Error Parsing configuration from NLog.config failed. Exception: NLog.NLogConfigurationException: Exception when parsing NLog.config.  ---> System.ArgumentException: Target cannot be found: 'EventLog'
   at NLog.Config.Factory`2.CreateInstance(String itemName)
   at NLog.Config.LoggingConfigurationParser.ParseTargetsElement(ILoggingConfigurationElement targetsElement)
   at NLog.Config.LoggingConfigurationParser.ParseNLogSection(ILoggingConfigurationElement configSection)
   at NLog.Config.LoggingConfigurationParser.LoadConfig(ILoggingConfigurationElement nlogConfig, String basePath)
   at NLog.Config.XmlLoggingConfiguration.ParseNLogElement(ILoggingConfigurationElement nlogElement, String filePath, Boolean autoReloadDefault)
   at NLog.Config.XmlLoggingConfiguration.Initialize(XmlReader reader, String fileName, Boolean ignoreErrors)
   --- End of inner exception stack trace ---
2019-06-12 10:27:51.4347 Warn Failed loading config from NLog.config. Invalid XML?
2019-06-12 10:27:51.4597 Debug Watching path 'C:\Repositories\DataPicker\DataPicker\DataPicker.Api' filter 'NLog.config' for changes.
2019-06-12 10:27:51.4597 Debug --- NLog configuration dump ---
2019-06-12 10:27:51.4680 Debug Targets:
2019-06-12 10:27:51.4680 Debug Rules:
2019-06-12 10:27:51.4680 Debug --- End of NLog configuration dump ---
2019-06-12 10:27:51.4680 Trace FindReachableObject<System.Object>:
2019-06-12 10:27:51.4680 Info Found 0 configuration items
2019-06-12 10:27:51.4889 Debug Targets not configured for logger: DataPicker.Api.Program
2019-06-12 10:27:55.2679 Debug ScanAssembly('NLog.Web.AspNetCore, Version=4.0.0.0, Culture=neutral, PublicKeyToken=5120e14c03d0593c')
2019-06-12 10:27:55.7717 Debug Hide assemblies for callsite
2019-06-12 10:27:55.7717 Trace Assembly 'NLog.Extensions.Logging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=5120e14c03d0593c' will be hidden in callsite stacktrace
2019-06-12 10:27:55.7855 Debug ScanAssembly('NLog.Extensions.Logging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=5120e14c03d0593c')
2019-06-12 10:27:55.7855 Trace Assembly 'Microsoft.Extensions.Logging, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' will be hidden in callsite stacktrace
2019-06-12 10:27:55.7855 Trace Assembly 'Microsoft.Extensions.Logging.Abstractions, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' will be hidden in callsite stacktrace
2019-06-12 10:27:55.8068 Debug Targets not configured for logger: Microsoft.AspNetCore.Hosting.Internal.ApplicationLifetime
2019-06-12 10:27:55.8068 Debug Targets not configured for logger: Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv
2019-06-12 10:27:55.8178 Debug Targets not configured for logger: Microsoft.AspNetCore.Server.Kestrel
2019-06-12 10:27:55.8465 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.TypeForwardingActivator
2019-06-12 10:27:55.8465 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager
2019-06-12 10:27:55.8622 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.CngGcmAuthenticatedEncryptorFactory
2019-06-12 10:27:55.8622 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.CngCbcAuthenticatedEncryptorFactory
2019-06-12 10:27:55.8622 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ManagedAuthenticatedEncryptorFactory
2019-06-12 10:27:55.8776 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiXmlEncryptor
2019-06-12 10:27:55.8776 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository
2019-06-12 10:27:55.9084 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.KeyManagement.DefaultKeyResolver
2019-06-12 10:27:55.9084 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider
2019-06-12 10:27:55.9084 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.Internal.DataProtectionStartupFilter
2019-06-12 10:27:55.9835 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiXmlDecryptor
2019-06-12 10:27:56.1465 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Formatters.JsonPatchInputFormatter
2019-06-12 10:27:56.1465 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Formatters.JsonInputFormatter
2019-06-12 10:27:56.1674 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.RazorPages.Internal.RazorProjectPageRouteModelProvider
2019-06-12 10:27:56.2420 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker
2019-06-12 10:27:56.2524 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Razor.Internal.RazorViewCompiler
2019-06-12 10:27:56.2524 Debug Targets not configured for logger: Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtector
2019-06-12 10:27:56.2707 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.ViewFeatures.CookieTempDataProvider
2019-06-12 10:27:56.2707 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker
2019-06-12 10:27:56.2814 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Internal.ActionSelector
2019-06-12 10:27:56.2814 Debug Targets not configured for logger: Microsoft.AspNetCore.Mvc.Internal.MvcRouteHandler
2019-06-12 10:27:56.2984 Debug Targets not configured for logger: Microsoft.AspNetCore.Builder.RouterMiddleware
2019-06-12 10:27:56.3256 Debug Targets not configured for logger: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware
2019-06-12 10:27:56.3523 Debug Targets not configured for logger: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware
2019-06-12 10:27:56.3523 Debug Targets not configured for logger: Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware
2019-06-12 10:27:56.3592 Debug Targets not configured for logger: Microsoft.AspNetCore.HttpOverrides.ForwardedHeadersMiddleware
2019-06-12 10:27:56.3592 Debug Targets not configured for logger: Microsoft.AspNetCore.Hosting.Internal.WebHost
2019-06-12 10:27:56.3783 Debug Targets not configured for logger: Microsoft.AspNetCore.Hosting.Internal.HostedServiceExecutor

Answer 1

You have misplaced the log attribute in <logger> instead of <target>. Please try the following config:

<?xml version="1.0" encoding="utf-8" ?>
<nlog autoReload="true" throwExceptions="false"
  internalLogLevel="Error" internalLogFile="NLogError.log"
  xmlns="http://www.nlog-project.org/schemas/NLog.xsd" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>
    <target name="EventLog" xsi:type="EventLog"
      layout="${longdate} ${level} ${callsite} -> ${message} 
      ${exception:format=Message,StackTrace}"
      source="MonDBSvc" log="Application" />
  </targets>
  <rules>
    <logger name="MonDbSvc" minlevel="Error" writeTo="EventLog" />
  </rules>
</nlog>

UPDATE

Also, please try to initialize your logger in c# file like below:

var logger = LogManager.GetLogger("MonDbSvc");

Answer 2

About the Target cannot be found: 'EventLog' error

The "Target cannot be found" error is thrown when the Target class cannot be instantiated. As you could plug in targets into NLog, NLog don't know which are available forehand. Please also note that not all targets are available in all platforms.

The latter is als the case for the eventlog target - is not available in all platforms:

See https://github.com/NLog/NLog/wiki/EventLog-target

Platforms Supported: Limited (Only available for Net35, Net40, Net45 and NetStandard 2.0. Note: NetStandard 2.0 must use NLog.WindowsEventLog package)

If you're using .NET Core 1.x, it won't work - Microsoft did not port the API because the eventlog is Windows only.

For .NET Core 2 you need to install the NLog.WindowsEventLog package and add this in your nlog.config (on top):

<extensions>
    <add assembly="NLog.WindowsEventLog"/>
</extensions>

Please note: the error you're posting will tell that the target is unavailable. The config seems to be valid and no changes are needed in the logger code. Also NLog.config or nlog.config is not an issue.

Elastic search

Maybe I missed it, but why using the eventlog target for Elastic search? There is a Elastic search target. Package https://www.nuget.org/packages/NLog.Targets.ElasticSearch

This package supports .NET Standard 1.3+ and .NET Standard 2+

usage:

<nlog>
  <extensions>
    <add assembly="NLog.Targets.ElasticSearch"/>
  </extensions>
  <targets>
    <target name="elastic" xsi:type="BufferingWrapper" flushTimeout="5000">
      <target xsi:type="ElasticSearch"/>
    </target>
  </targets>
  <rules>
    <logger name="*" minlevel="Info" writeTo="elastic" />
  </rules>
</nlog>

Answer 3

Thanks to all of you!

I got it working, logs are writing into Elasticsearch now. My current configuration looks like that:

<?xml version="1.0" encoding="utf-8" ?>
<nlog autoReload="true" throwExceptions="false"
      internalLogLevel="Error" internalLogFile="NLogError.log"
      xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
  </extensions>
  <targets>
    <target xsi:type="Network"
        name="CentralLog"
        newLine ="false"
        maxMessageSize="65000"
        connectionCacheSize="5"
        encoding="utf-8"
        keepConnection="false"
        maxQueueSize="100"
        address="tcp://abc.xyz.org:5544"
        onOverflow="Split">
     <layout type="JsonLayout">
      <attribute name="machinename" layout="${machinename}" />
      <attribute name="level" layout="${level:upperCase=true}" />
      <attribute name="processname" layout="${processname}" />
      <attribute name="processid" layout="${processid}" />
     </layout>
   </target>
  </targets>
  <rules>
  <logger name="*" minlevel="Trace" writeTo="CentralLog" />
  </rules>
</nlog>

Answer 4

You can find more details here for logging the message:

https://github.com/NLog/NLog.Web/wiki/Getting-started-with-ASP.NET-Core-2

Use this to provide the access to event log: https://www.nuget.org/packages/NLog.WindowsEventLog

Added the tag in the config file:

<extensions>
    <add assembly="NLog.Web.AspNetCore"/>
</extensions>

Hope this will helps you.