Hello, This error is most likely being caused by the prescence of a third-party copy of the Qt library. (Most likely installed by the Nessus security scanner) Alteratively, it could also perhaps be a local copy without the qt-copy patches installed to /usr/share/local or somesuch. The output of "ldd -d -r /usr/bin/okular" should let us know if this is the case. Thanks, Jonathan