It’s a good idea for all the assemblies in a single solution to have the same version number, but the default in Visual Studio is for each project to have it’s own AssemblyInfo.cs file, each with it’s own version number. However it’s easy to share a single Version.cs file between all the projects.

First create the Version.cs file as a solution item (right click on the solution, Add, New Item). It should look something like this:

using System.Reflection;

[assembly: AssemblyVersion("1.0.1.442")]
[assembly: AssemblyFileVersion("1.0.1.442")]

Now remove those same lines (AssemblyVersion and AssemblyFileVersion) from the AssemblyInfo.cs file in each project in the solution.

The next step to add a link to the Version.cs file to each project. Right click on the project and choose ‘Add New Item’ and then ‘Existing Item’. Browse to the Version.cs file in the solution root directory and add it as a link (click on the little drop down arrow on the ‘Add’ button in the file dialogue):

Do this to all your projects. Now you only have to maintain the version number for the whole solution in one place. Nice!

It’s common practice to integrate version numbering with continuous integration. This usually works by having the CI build process update the version number with the build number before each build. Having the number represented in one place makes that much easier.