How to use 2 different log4net assemblies - each targeted for different versions of the .Net Framework, in the same solution?

Question

My question is closely related to the one

Log4Net : 2 libraries need 2 different version of it

but slightly different.

While our Main EXE is compiled with .Net Framework 4.0, some of the referenced assemblies are compiled for Framework v2.0 and we have to add logging within those assemblies as well. While we had chosen log4net v1.2.11 (the latest, I believe), we are hitting a road-block in using the 2 different assembles in our solution.

@RedFilter - the log4net assemblies have the same file name, and if you copy one the other can no longer be found - the exception is thrown that assembly (with full assembly name) cannot be loaded. — veljkoz, Oct 09 '12 at 14:44
Sorry for not elaborating the "roadblock" earlier. To add on, I even tried renaming the original "log4net.dll"s as "log4net_dotNet2.dll" and "log4net_dotNet4.dll". But the CLR seems to be expecting only log4net.dll. Maybe, I am missing some fundamental understanding of .Net here. I am yet to look into the the [link](http://msdn.microsoft.com/en-us/library/7wd6ex19.aspx) provided in the answer by "veljkoz" down below — Srivathsan M, Oct 10 '12 at 05:21

veljkoz · Answer 1 · 2012-10-10T08:12:10.870

First off, you can't have all of the dll's in the same folder (as you already found).

Here it's explained how the runtime tries to load the assembly.

Using this knowledge, you could:

Redirect assembly versions (if they are compatible, which I think they are) - e.g. from old log4net dll to the new dll
Specify assemlby location that should be used when loading assemblies (e.g. put it in \Libs folder, and reference that)
Load the assembly manually - theoretically, this could work because it's loading that assembly into the domain.

One example, taken from here ("Multiple Assemblies with the Same Name"):

<dependentAssembly>
  <assemblyIdentity name="Server" publicKeyToken="c0305c36380ba429" /> 
     <codeBase version="1.0.0.0" href="v1/Server.dll"/>
     <codeBase version="2.0.0.0" href="v2/Server.dll"/>
</dependentAssembly>

I like the Assembly.LoadFrom solution. Anyway you should also be able to register both of them in GAC. — Felix K., Oct 10 '12 at 08:16

score 0 · Answer 2 · answered Oct 09 '12 at 14:39

0

I think it's safe just use the version targeting .net 2.0.

answered Oct 09 '12 at 14:39

xing

447
2
6

score 0 · Answer 3 · answered Oct 09 '12 at 15:18

You can use this section

<configuration>
  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="2.0" />
  </startup>
</configuration>

Link : http://msdn.microsoft.com/fr-fr/library/vstudio/bbx34a2h.aspx

Link : http://msdn.microsoft.com/en-us/library/w4atty68(v=vs.71).aspx

How to use 2 different log4net assemblies - each targeted for different versions of the .Net Framework, in the same solution?

3 Answers3