Readonly property

This warning category is spelled c{[read-only-property]} by qmllint.

Cannot assign to read-only property

What happened?

A read-only property was written.

Why is this bad?

The QML engine will throw a Type Error when it sees the write to a read-only property.

Example

import QtQuick

Item {
    id: root
    readonly property int someNumber: 10

    Component.onCompleted: {
        someNumber = 20  // not ok: TypeError: Cannot assign to read-only property
    }
}

To fix this warning, remove the write to the read-only property, write to another non-read-only property, or remove the readonly modifier if you are the author of the property definition.