Q:

Invalid property assignment: "anchors" is a read-only property

Wrote a simple QML app, and it's complaining that I can't set the anchors for a text item. 
qrc:/main.qml:13 Invalid property assignment: "anchors" is a read-only property

What's going on? 
import QtQuick 2.7
import QtQuick. Controls 2.0

ApplicationWindow {
    visible: true
    width:320; height:240
    title: "Driver Confidence"

    property real accSpeed: 29.0576

    Text {
        text: accSpeed.toFixed(0) + " m/s"
        anchors: { top:parent.top; left:parent.left }
    }
}

A:

The problem is a simple syntax error combined with a confusing error message.  The anchors line should not have a colon after anchors:
anchors { top:parent.top; left:parent.left }

With the colon it is trying to evaluate the block as a JavaScript expression (which is invalid) and then assign the result to overwrite the entire anchors object.