How do you get the current project directory from C# code when creating a custom MSBuild task?

If you want ot know what is the directory where your solution is located, you need to do this:

 var parent = Directory.GetParent(Directory.GetCurrentDirectory()).Parent;
            if (parent != null)
            {
                var directoryInfo = parent.Parent;
                string startDirectory = null;
                if (directoryInfo != null)
                {
                    startDirectory = directoryInfo.FullName;
                }
                if (startDirectory != null)
                { /*Do whatever you want "startDirectory" variable*/}
            }

If you let only with GetCurrrentDirectory() method, you get the build folder no matter if you are debugging or releasing. I hope this help! If you forget about validations it would be like this:

var startDirectory = Directory.GetParent(Directory.GetCurrentDirectory()).Parent.Parent.FullName;