Sentinel.v3.5Client error in ClickOnce app install

We have had bad experiences in the past deploying desktop applications based on the .Net Framework version 3.5, largely due to the huge payload required on the end user’s system to run our relatively simple application.

When SP1 of Visual Studio 2008 was announced to have an option to trim down the bits to be downloaded, we were naturally excited to put it into place on our newest product. In a VB.NET application, this option is called “Client-only Framework subset”, it is on the Advanced Compiler Settings window shown by clicking Advance Compile Options… on the Compile tab of My Project, and in a C#.NET application, the Client-only Framework subset check box is right under Target Framework on the Application tab shown by right clicking on the project file and selecting Properties.

Excited until, of course, we tried for the very first time to run the ClickOnce installer for our product on a clean Windows XP SP3 virtual machine and received the following error:

Unable to install or run the application. The application requires that
assembly Sentinel.v3.5Client Version be installed in the Global
Assembly Cache (GAC) first.

I did some quick investigating and found that, for the most part, the suggested solution was to turn off the client only subset option. Bugger!

This did not sit well with me, so I did a little more digging. I did not think that there were any kind of items added to the code that would require namespaces not included in the client only framework, so I went through all of the property pages for the project.

On the Publish tab, I clicked on Preqrequisites, and noticed that my application was including prerequisites for Windows Installer 3.1, .NET Framework 3.5, and SQL Server Compact 3.5. On a lark, I turned off the prerequisite for .NET Framework 3.5 and turned on the prerequisite for .NET Framework 3.5 SP1, built the ClickOnce installer, and voila! It is now working like a champ.