DLL versioning error

Question

I've got a web site that sporadically throws the following error:

Server Error in '/' Application.

Could not load file or assembly 'ICSharpCode.SharpZipLib, Version=0.85.3.365, Culture=neutral, PublicKeyToken=1b03e6acf1164f73' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Now I know that I do have a dependency on this DLL, but I have version 0.85.5 on my system. I have systematically deleted every older version of the DLL from the server, recompiled everything and republished. But no matter what I do, it seems that after every republish, the first one or two times that someone visits the site, they get this error. Then after refreshing once or twice, the error goes away and the site functions as normal.

What makes it even more weird is if I look at the line of code where the error is thrown:

URLRewriter.ProcessRewritingResult(status, excludedEnum, siteName, viewMode, relativePath);

URLRewriter is a class from a 3rd party package (Kentico CMS - CMS.URLRewritingEngine.dll). I ran Dependency Walker on that DLL and found no dependencies whatsoever on ICSharpCode.SharpZipLib.

Any ideas how to fix this?

EDIT: At @JeremyThompson's suggestion, I ran Process Monitor to catch the error. Here's a screen dump, with relevant pieces highlighted (and one folder name obscured for privacy reasons). You can view it full size by right-clicking on it, etc...

EDIT: Here's a load trace from the error. Does this help?

=== Pre-bind state information ===

LOG: User = MY-SERVER-12\Administrator

LOG: DisplayName = ICSharpCode.SharpZipLib, Version=0.85.3.365, Culture=neutral, PublicKeyToken=1b03e6acf1164f73 (Fully-specified)

LOG: Appbase = file:///C:/inetpub/wwwroot/MySite/

LOG: Initial PrivatePath = C:\inetpub\wwwroot\MySite\bin

Calling assembly : CMS.WebAnalytics, Version=6.0.4377.2467, Culture=neutral, PublicKeyToken=834b12a258f213f9.

===

LOG: This bind starts in default load context.

LOG: Using application configuration file: C:\inetpub\wwwroot\MySite\web.config

LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config

LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config.

LOG: Post-policy reference: ICSharpCode.SharpZipLib, Version=0.85.3.365, Culture=neutral, PublicKeyToken=1b03e6acf1164f73

LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/root/9760eb69/275bb3db/ICSharpCode.SharpZipLib.DLL.

LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/root/9760eb69/275bb3db/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.DLL.

LOG: Attempting download of new URL file:///C:/inetpub/wwwroot/MySite/bin/ICSharpCode.SharpZipLib.DLL.

LOG: Attempting download of new URL file:///C:/inetpub/wwwroot/MySite/bin/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.DLL.

LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/root/9760eb69/275bb3db/ICSharpCode.SharpZipLib.EXE.

LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/root/9760eb69/275bb3db/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.EXE.

LOG: Attempting download of new URL file:///C:/inetpub/wwwroot/MySite/bin/ICSharpCode.SharpZipLib.EXE.

LOG: Attempting download of new URL file:///C:/inetpub/wwwroot/MySite/bin/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.EXE.

Answer 1

So it turns out that Kentico has its own dependency on ICSharpCode.SharpZipZip.dll - and it's expecting to find the older version. I found a similar solution here. By inserting the following block into my web.config file, it seems I have finally banished this error!

<runtime>
  <assemblyBinding>
    <dependentAssembly>
      <assemblyIdentity name="ICSharpCode.SharpZipLib" publicKeyToken="1b03e6acf1164f73"/>
      <bindingRedirect oldVersion="0.85.3.365" newVersion="0.85.5.452"/>
    </dependentAssembly>
  </assemblyBinding>
</runtime>

What I still don't understand is, why didn't Dependency Tracker show up this dependency?

EDIT: Oh dear, this didn't solve it after all. It seems to happen less frequently now, but after restarting IIS today, one of our testers got the old error message again! :-(