"Web application at ... could not be found" Error on MOSS 2007 x64

I encountered a rather nasty bug last week with Microsoft Office SharePoint Server (MOSS) 2007 when trying to run an x86 process (that utilizes the SharePoint API) on an x64 server.

To provide the simplest repro possible, I created a sample console application that prints the title of a SharePoint site:

 using System;

using Microsoft.SharePoint;

namespace Fabrikam.Demo.PrintSharePointSiteTitle
{
    class Program
    {
        static void Main(
            string[] args)
        {
            if (args.Length < 1)
            {
                Console.Error.WriteLine(
                    "Usage: PrintSharePointSiteTitle {site URL}");

                Environment.Exit(1);
            }

            string siteUrl = args[0];

            using (SPSite site = new SPSite(siteUrl))
            {
                Console.WriteLine(
                    "Title: {0}",
                    site.RootWeb.Title);
            }
        }
    }
}

Note that by default, Visual Studio projects set the platform target to Any CPU. Thus when you run this program on an x64 server, the process runs natively in 64-bit and everything works as expected:

C:\NotBackedUp\Temp\PrintSharePointSiteTitle\bin\Debug>PrintSharePointSiteTitle.exe https://fabrikam-local
Title: Fabrikam

However, if you change the platform target to x86 and thus force the process to run in 32-bit then things don't go well:

C:\NotBackedUp\Temp\PrintSharePointSiteTitle\bin\Debug>PrintSharePointSiteTitle.exe https://fabrikam-local

Unhandled Exception: System.IO.FileNotFoundException: The Web application at https://fabrikam-local could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.
at Microsoft.SharePoint.SPSite..ctor(SPFarm farm, Uri requestUri, Boolean contextSite, SPUserToken userToken)
at Microsoft.SharePoint.SPSite..ctor(String requestUrl)
at Fabrikam.Demo.PrintSharePointSiteTitle.Program.Main(String[] args) in C:\NotBackedUp\Temp\PrintSharePointSiteTitle
\Program.cs:line 22

I could certainly understand getting a BadImageFormatException in this scenario (in other words, if the platform target for Microsoft.SharePoint.dll was set to x64, then you shouldn't expect to be able to load it from a 32-bit process). Instead I get a "bogus" FileNotFoundException suggesting my Web application doesn't exist.

At this point, you're probably thinking something like "Jeremy, why would you possibly want to run a 32-bit process on a 64-bit server?" Great question...

There are at least a couple of scenarios that I'm aware of:

• First, you might want to run some Visual Studio unit tests that access a live SharePoint site. These unit tests work great when you are developing on an x86 MOSS 2007 VM. However, they "blow chunks" on an x64 development VM. [Oh, and please don't get me started on the whole "mocking" topic for unit testing SharePoint. That could get me going for hours -- and I really do have more important things to do today ;-)  ]
• Second, you might have written a utility, let's say, something like ImportPages.exe, that bulk loads pages into a SharePoint site using an Excel input file. Since the SharePoint API in MOSS 2007 is not "remoteable" (without switching to calling Web services), you must run ImportPages.exe directly on one of the SharePoint servers in the farm.

It's the latter scenario in which I first encountered this bug. However, rather than going into the details here, I want to cover the ImportPages.exe utility in a separate post.