The imported project WebApplication.targets was not found. Confirm that the path in the declaration is correct and that the file exists on disk.

The imported project WebApplication.targets was not found. Confirm that the path in the <Import> declaration is correct and that the file exists on disk.

Quick Solution (not considering MSBuild versions):

Copy the folder with the latest version number from C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio and paste it in C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio and renamed it to the version that is missing. Example:
Copy and paste:
  C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0 
as:
  C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0

Note: In the above solution, "C:\Program Files (x86)\" may be "C:\Program Files\" on your machine.