Could not load file or assembly log4net

Question

I have added log4net to my project and it is working just fine on my machine, but when I sent the release version of my application to my colleague, he receives this FileNotFoundException:

Could not load file or assembly 'log4net, Version=1.2.13.0, Culture=neutral, PublicKeyToken=669e0ddf0bb1aa2a'

But the strange thing is that in my app.config I'm not even using the above version of log4net:

<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
<sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<section name="BizWizard.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>
</sectionGroup>

Look at http://stackoverflow.com/questions/8743992/how-do-i-work-around-log4net-keeping-changing-publickeytoken May be this is what is needed in your case. — csprabala, Oct 27 '14 at 09:33
@csprabala I am trying to do the fixes. But why is it working fine on my machine? — disasterkid, Oct 27 '14 at 09:40
I know this sounds stupid, but did you send the log4net DLL's with your application to your colleague? — Bernd Linde, Oct 27 '14 at 09:40
@BerndLinde yes both log4net.dll and log4net.xml are included in the folder. — disasterkid, Oct 27 '14 at 09:41
Are both systems 64bit? (Reference [here](http://stackoverflow.com/questions/10137023)) — Bernd Linde, Oct 27 '14 at 09:43
Do your colleague use "global assembly cache"? Are some of your dll's being loaded from somewhere else on his computer? — Jan Petter Jetmundsen, Oct 27 '14 at 10:19
@JanPetterJetmundsen log4net is the only dll we are using in this program. — disasterkid, Oct 27 '14 at 10:20
Similar question here - [Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821'](https://stackoverflow.com/q/30611640/465053) — RBT, Jul 22 '21 at 06:11

score 9 · Answer 1 · answered Jan 25 '17 at 16:51

9

Ran into the same problem. LinqToExcel library was using different version of log4net.

To solve it:

Delete the old log4net version in References.
Go to Tools, Nuget Packet Manager, Package Manager Console.
Run:

Install-Package log4net -Version 2.0.3

More details here:

https://www.nuget.org/packages/log4net/2.0.3

answered Jan 25 '17 at 16:51

live-love

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The problem with this is, when something else has a dependency on the new version :( – Jessica Nov 22 '19 at 12:51

score 7 · Answer 2 · answered Oct 27 '14 at 10:13

Do you use other third party libraries? Maybe one of them requires this particular version of log4net. If this is the case, this can be resolved using assembly binding in your applications app.config file.

<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="log4net" publicKeyToken="669e0ddf0bb1aa2a" />
      <codeBase version="1.2.13.0" href="log4netv1.2.13.0\log4net.dll" />
    </dependentAssembly>
  </assemblyBinding>
</runtime>

and the put this the 1.2.13.0 version of log4net in a sub-folder called log4netv1.2.13.0

You may also try to redirecting all references to log4net to a specific (your) version using bindingRedirect. http://msdn.microsoft.com/en-us/library/7wd6ex19(v=vs.110).aspx

I just downgraded to log4net 1.2.0 and it started working. Since I am not looking for problems in the future I think I'm gonna stick to this for now. — disasterkid, Oct 27 '14 at 11:36
put some folder, redirect... what are you talking about? All use nuget packages for years! they you can't simply put library in a folder you want and hack the problem! — Artem A, Apr 07 '17 at 13:58

score 0 · Answer 3 · answered Mar 24 '22 at 07:55

0

You can check in the Nuget-Package-Manager (Tools-->Nuget-Package-Manager) if you have installed the log4net-Package in other Projects of this solution as well. If so, you can upgrade them to the same version. That worked for me.

answered Mar 24 '22 at 07:55

Julian Müller

59
4

Could not load file or assembly log4net

3 Answers3

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