QOpenGLShader::link: Vertex info error: must write to gl_Position

JesusM

I am having a problem when I link my shader program. This is the function that throws the error:

GLuint shaderProgram::createShaderProgram(const char *fileName) {
    // Creamos el shader program y almacenamos su identificador
    if (handler) {
        shaderP = new QOpenGLShaderProgram();
        handler = shaderP->create();
        if (!handler) {
            fprintf(stderr, "Cannot create shader program: %s.\n", fileName);
            return 0;
        }
    }
    // Cargamos y compilamos cada uno de los shader objects que componen este
    // shader program
    char fileNameComplete[256];
    strcpy_s(fileNameComplete, fileName);
    strcat_s(fileNameComplete, "-vert.glsl");
    QOpenGLShader* vertex = new QOpenGLShader(QOpenGLShader::Vertex);
    GLuint vertexShaderObject = compileShader(fileNameComplete, QOpenGLShader::Vertex,vertex);
    if (vertexShaderObject == 0) {
        return 0;
    }
    strcpy_s(fileNameComplete, fileName);
    strcat_s(fileNameComplete, "-frag.glsl");
    QOpenGLShader* fragment = new QOpenGLShader(QOpenGLShader::Fragment);
    GLuint fragmentShaderObject = compileShader(fileNameComplete, QOpenGLShader::Fragment, fragment);
    if (fragmentShaderObject == 0) {
        return 0;
    }
    // Asociamos los shader objects compilados sin errores al shader program
    shaderP->addShader(vertex);
    shaderP->addShader(fragment);

    // Enlazamos el shader program y comprobamos si hay errores
    handler = shaderP->link(); //The error is thrown here
    if(!handler)
    {
        QString error = shaderP->log();
        std::cout<< error.toStdString()<<std::endl;
        return 0;
    }
    else {
        linked = true;
    }
    return handler;
}

It says : (0) : error C5145: must write to gl_Position.
But gl_Position is an OpenGL variable that I can't manage. I have used these shaders in other Visual Studio with C++ programming and they work well.

These are the shaders:

vertex:

#version 400

layout (location = 0) in vec3 vPosition;

uniform mat4 mvpMatrix;
uniform vec3 vColor;
uniform float pointSize;
out vec4 destinationColor;

void main()
{
	gl_PointSize = pointSize;
	destinationColor = vec4(vColor, 1.0);
	gl_Position = mvpMatrix * vec4(vPosition, 1.0);
}

fragment:

#version 400

in vec4 destinationColor;

out vec4 fColor;

void main()
{
	vec2 coord = gl_PointCoord-vec2(0.5);
	if(length(coord) > 0.5)
	{
		discard;
	}
	fColor = destinationColor;
}