It depends on whether you use any function related to the tool chain 15, but if you do not, you must open the text editor .csproj and change the version of the tools to 14.
<?xml version="1.0" encoding="utf-8"?> <Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
If the above does not work for you, recreate the project in Visual Studio 2015; which will use version 14 of the tools. You should be able to open the project in Visual Studio 2017 and in SharpDevelop.
source share