Running two versions of MongoDB assemblies at the same time - asp.net

Question

All,
My Project - (VS 2010 / .NET 4 / ASP.NET application, my web application lives inside Sitefinity as a Sitefinity application)
I have two versions of the MongoDB assemblies. I would like to run these side-by-side in my web application. Here's my setup:
\bin\AuxFiles\[1.8.3.9] assemblies
\bin\[1.4.x.x] assemblies
Web config:
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="MongoDB.Bson" publicKeyToken="f686731cfb9cc103" culture="neutral" />
<codeBase version="1.4.2.4500" href="bin\MongoDB.Bson.dll" />
<codeBase version="1.8.3.9" href="bin\AuxFiles\MongoDB.Bson.dll" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="MongoDB.Driver" publicKeyToken="f686731cfb9cc103" culture="neutral" />
<codeBase version="1.4.2.4500" href="bin\MongoDB.Driver.dll" />
<codeBase version="1.8.3.9" href="bin\AuxFiles\MongoDB.Driver.dll" />
</dependentAssembly>
</assemblyBinding>
When the application starts, it loads the 1.4.x.x assemblies by default. When I go to the page that uses the 1.8.3.9 version of assemblies I get an error:
Server Error in '/' Application.
Could not load file or assembly 'MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.IO.FileLoadException: Could not load file or assembly 'MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Source Error: ....
Source File: ...... Line: 18
Assembly Load Trace: The following information can be helpful to determine why the assembly 'MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103' could not be loaded.
=== Pre-bind state information ===
LOG: DisplayName = MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103
(Fully-specified)
LOG: Appbase = file:///C:/DEV/Visual Studio 2010/WebStoreApp/WebStoreApp/
LOG: Initial PrivatePath = C:\DEV\Visual Studio 2010\WebStoreApp\WebStoreApp\bin
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\DEV\Visual Studio 2010\WebStoreApp\WebStoreApp\web.config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/d73c4379/cb2aee95/MongoDB.Driver.DLL.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/d73c4379/cb2aee95/MongoDB.Driver/MongoDB.Driver.DLL.
LOG: Attempting download of new URL file:///C:/DEV/Visual Studio 2010/WebStoreApp/WebStoreApp/bin/MongoDB.Driver.DLL.
WRN: Comparing the assembly name resulted in the mismatch: Minor Version
ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.
Stack Trace:
[FileLoadException: Could not load file or assembly 'MongoDB.Driver, Version=1.8.3.9, Culture=neutral, PublicKeyToken=f686731cfb9cc103' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
System.Web.UI.Control.OnLoad(EventArgs e) +92
System.Web.UI.Control.LoadRecursive() +54
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint
UPDATE 1:
I have tried to rename my new 1.8.x.x assemblies from MongoDB.Driver.dll to MongoDB.Driver.exe so the files can co-exist under same directory (the older assemblies have extension .dll, the new version of the assemblies have extension .exe) but the loader seems not to pickup the assemblies. My understanding is that the loader always tries .dlls first, then tries .exes second. I am a bit puzzled.
UPDATE 2:
I have created a console application w/ exactly identical setup of my dual references and the app config entries that you see here,- and the application works, it executes 2 versions of the Mongo dll. The question is now, why doesn't this setup work in my Web application? Are my directories wrong? If you look below at the probing for the assemblies, it never checks my AuxFiles directory, it appears it simply ignores my configuration for side-by-side execution in web.config.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/d73c4379/cb2aee95/MongoDB.Driver.DLL.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/d73c4379/cb2aee95/MongoDB.Driver/MongoDB.Driver.DLL.
LOG: Attempting download of new URL file:///C:/DEV/Visual Studio 2010/WebStoreApp/WebStoreApp/bin/MongoDB.Driver.DLL.
WRN: Comparing the assembly name resulted in the mismatch: Minor Version
ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.
UPDATE 3:
Found the issue but I am not sure of the details of this solution. The web.config file has 'configuration' root element w/ the following namespace declaration - 'xmlns=http://schemas.microsoft.com/.NetConfiguration/v2.0'.
The root element is fine but the specified namespace is causing my 'runtime' element to be ignored. Removing the namespace from the configuration element fixes everything.

Answer 1

Found the issue:
The 'configuration' root element in the web.config file contains the following namespace declaration - 'xmlns=http://schemas.microsoft.com/.NetConfiguration/v2.0'. Removing the namespace from the configuration element fixes everything.
Why the ns? It is more of a bug then anything in VS and has really no real purpose but mess up your intellisense and in my case the runtime configuration. Read more about it:
http://weblogs.asp.net/scottgu/archive/2005/12/02/432077.aspx