Just for the record. I had the same problem (QVariant::load(QDataStream &s): type unknown to QVariant.) on SuSE 10.3 & 11.0 with both eric4-4.2.5 and eric4-4.3-snapshot-2009011. It appeared after installing rpms for the beta QT-Creator. The problem solved by removing ~/.config/Eric4 directory. Regards, Mikhail