The attempt to persist a QList<QString> using the QSettings.setValue() method seems to work well, but after restarting the application, the attempt to deserialize gives the error message:

QVariant::load: unknown user type with name QList<QString>

persisting code:

QSettings settings; 
 QList<QString> data {"first", "second", "third"};
 settings.setValue("sourceList", QVariant::fromValue(data));

primitive types of objects are working well.

I am porting an existing application written for macOS and Windows to Linux. On Windows and macOS it seems to work, but I cannot verify this.

After analyzing the existing code, I identified, that a registration of an stream operator, before the QApplication is instantiated, solves the problem.

qRegisterMetaTypeStreamOperators<QList<QString>>("Data");
QApplication a(argc, argv);

Why this seems not to be necessary on non linux environment is not clear to me.