Visual Studio Builds Projects Every Time I Run

The cause could be many things, so without having your solution + projects, we can only guess.

The typical way I handle this problem is by narrowing it down with a binary search. That is,

1. I build everything.
2. Next I find something in the middle of the build order and build that project. If something that that project depends on is the culprit, you'll experience the issue. If something that it doesn't depend on has the problem you won't (i.e. it will say all projects skipped).
3. Now you repeat this process until you narrow it down to (hopefully) the project that has started causing the problem.

This (of course) only works if there is a single project that introduced the new problem (which is likely).

One of the culprits in my specific situation was having an x64 project reference an x86 project that wasn't selected to be built in the x64 configuration.

Go to Tools -> Options -> Project and Solutions -> Build and Run. Look at the options there. 'Only build startup projects and dependencies on Run' should be checked.

Additionally, you can set the build output (in the same options screen) to Detailed or Diagnostic to see if you can find any clues why the projects are built every time.

I'll share the best answer i've found here on stackoverflow and combined with matt smith's accepted answer here, i´ve reached the root cause of my problem:

By configuring Visual Studio to log the build output in a "Diagnostic" manner, as explained in this answer: https://stackoverflow.com/a/29649259/2740778, the very first line on the output explains why MSBuild determines to rebuild a project.

So, if you have, let's say 3 projects into a solution:

• Library0
• Library1
• Application

referenced this way: Application references Library1 and this one references Library0. By selecting "Build" for the Application project, the first time it should build all the referenced projects in order. But from now on, if no changes where made, pressing "Build" should not build anything, because MSBuild detects that changes where not made. A similar log output should be displayed:

========== Build: 0 succeeded, 0 failed, 3 up-to-date, 0 skipped ==========

But now, if changes where made, if you have the MSBuild log output level on "Diagnostic", the first line in the output window will display the reason of why does Visual Studio decides to build a project, like here:

Project 'Library0' is not up to date. Input file 'c:\Library0\Class1.cs' is modified after output file 'c:\Library0\bin\Debug\Library0.pdb'.