side by side configuration is incorrect

Someone with a Windows 7 64-bit laptop got this error:

“Error: The application has failed to start because the side by side configuration is incorrect”.

Oh yeah. Here’s where people pay the price for foot-dragging by most of the world’s software vendors in delivering 64-bit versions of their software.

The best answer I found to this on the mostly clueless Internet was this one from Microsoft Answers moderator Marilyn O:

Error message: “Side-by-side configuration is incorrect”

The machine is missing the correct C++ runtime components for your type of system. (x86 or x64).

Installing the following update resolved the issue.

Microsoft Visual C++ 2008 SP1 Redistributable Package (x86)

Microsoft Visual C++ 2008 SP1 Redistributable Package for (x64)

Microsoft Visual C++ 2010 Redistributable Package (x86)

Microsoft Visual C++ 2010 Redistributable Package (x64)

The most probable causes I can think of for this kind of problem are: (1) a subsequent update or install overwrote a required redistributable; or (2) installation of a 64-bit component for a previously installed piece of 32-bit software.

If the application in question is Microsoft Office, I think either of these is an even higher probability than with other software.

Many hardware vendors ship a stripped down version of MS Office with their systems, and not surprisingly this is usually 32-bit. Users then find they need to view a document in a “later” version of some component like PowerPoint, Excel or Word. At that point they download the most recent 64-bit copy of the viewer and wind up corrupting their Office configuration. In cases like this it may be necessary to replace the 64-bit software with its 32-bit equivalent (after removing the 64-bit code). Of course it would be better to go with all 64-bit, but that’s something many software vendors make difficult as they try to squeeze out another year or more of profits from their 32-bit portfolio.

For more diagnostic advice see Solved: side by side configuration problem in Office 2010 over on the Vista64 forum, and this blog post by the principal developer of Microsoft’s Side by side assembly (Sxs or WinSxs) architecture for resolving the historic “DLL Hell” problem.

The basic approach should be to start by opening up Event Viewer and backtracking from there.