QNetworkReply readAll error

[TorAn]

(Qt 5.3 version) I have a strange situation with the code that I moved from one project to another. Used to work just fine... Here is the code:

void onResult(QNetworkReply* r)
{
		QNetworkReply::NetworkError err = r->error(); // no error
		bool isfin = r->isFinished();                              // returns true;
		qint64 bta = r->bytesAvailable();                      // returns  988305 (correct size of a file I am trying to download)
		r->setReadBufferSize(0);                                  // to set read buffer to be unlimited size (per doc)
		QByteArray ba(bta+1000,'0');
		ba = r->readAll();                                            // UNHANDLED EXCEPTION at 0x5D8CA9E8 (msvcr120d.dll), qlist.h line 432
...
}

void onResult(QNetworkReply* r)
{
		QNetworkReply::NetworkError err = r->error(); // no error
		bool isfin = r->isFinished();                              // returns true;
		qint64 bta = r->bytesAvailable();                      // returns  988305 (correct size of a file I am trying to download)
		r->setReadBufferSize(0);                                  // to set read buffer to be unlimited size (per doc)
		QByteArray ba(bta+1000,'0');
		ba = r->readAll();                                            // UNHANDLED EXCEPTION at 0x5D8CA9E8 (msvcr120d.dll), qlist.h line 432
...
}

To copy to clipboard, switch view to plain text mode 

I am puzzled and will appreciate any advise or comment on what is going on and how to resolve it.

Details:
void onResult is a slot in a thread class:

class downloader : public QThread
{
	Q_OBJECT
public:
 
	downloadRebate() : QThread() {}
	void run() {
		_uploadman.reset(new QNetworkAccessManager());
..
                connect(_uploadman.get(), SIGNAL(finished(QNetworkReply*)), this, SLOT(onResult(QNetworkReply*)));
		_uploadman->get(upload);
		exec();
	}
private slots:
	void onResult(QNetworkReply* r);
..
}

class downloader : public QThread
{
	Q_OBJECT
public:

	downloadRebate() : QThread() {}
	void run() {
		_uploadman.reset(new QNetworkAccessManager());
..
                connect(_uploadman.get(), SIGNAL(finished(QNetworkReply*)), this, SLOT(onResult(QNetworkReply*)));
		_uploadman->get(upload);
		exec();
	}
private slots:
	void onResult(QNetworkReply* r);
..
}

To copy to clipboard, switch view to plain text mode