WCF 64 bit not working


I'm trying to develop a simple WCF service running in a 64 bit environment. I fire up VS2010 under Windows 7

New Solution -> WCF project -> Run -> It works fine.

As soon as I change the properties of the project in order to make it compile in 64 bit, running it throws the following exception:

Could not load file or assembly 'WcfService2' or one of its dependencies.

With the following Assembly Load Trace

=== Pre-bind state information ===
LOG: User = *****
LOG: DisplayName = WcfService2
WRN: Partial binding information was supplied for an assembly:
WRN: Assembly Name: WcfService2 | Domain ID: 4
WRN: A partial bind occurs when only part of the assembly display name is provided.
WRN: This might result in the binder loading an incorrect assembly.
WRN: It is recommended to provide a fully specified textual identity for the assembly,
WRN: that consists of the simple name, version, culture, and public key token.
WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.
LOG: Appbase = file:///d:/temp/WcfService2/WcfService2/
LOG: Initial PrivatePath = d:\temp\WcfService2\WcfService2\bin
Calling assembly : (Unknown).
LOG: This bind starts in default load context.
LOG: Using application configuration file: d:\temp\WcfService2\WcfService2\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: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL     file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/806f4cb8/df40e9e2/WcfService2.DLL.
LOG: Attempting download of new URL     file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/806f4cb8/df40e9e2/WcfService2/WcfService2.DLL.
LOG: Attempting download of new URL     file:///d:/temp/WcfService2/WcfService2/bin/WcfService2.DLL.
ERR: Failed to complete setup of assembly (hr = 0x8007000b). Probing terminated.

How can I overcome the problem? Any idea? Thanks


The WCF does compile after setting the Platform Target to AnyCPU, but I need to specifically set a 64 bit compilation because I'm working with SharePoint objects and a AnyCPU (or x86) compilation results in the very same problem and error described here (and in other places on the net).

So either I compile AnyCPU/x86 and I get an error from the integration with SharePoint or I set the target platform to 64 bit and I get an error from WCF.

asked on Stack Overflow Oct 1, 2010 by pistacchio • edited Oct 1, 2010 by pistacchio

3 Answers


I found the solution after a long research. The issue was that when you run the app with 64 bit the IIS Express also needs to run as a 64 bit process (by default it is a 32 bit process) . To make it 64 bit there is an option in Visual Studio. Tools --> Options --> Projects and Solutions --> Web Projects --> Use the 64 bit version of IIS Express.

Voila and it works.

answered on Stack Overflow Dec 10, 2018 by Tony

Is your WcfService2 assembly marked with Platform Target == x86? You should try ensuring that it is compiled to Any CPU instead. You'll find this setting in the Build page of the Visual Studio project settings.

answered on Stack Overflow Oct 1, 2010 by tomasr

Browse to Advanced Settings of Application Pool. Set "Enable 32-bit Applications" to true

answered on Stack Overflow May 4, 2011 by Ushanta

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