virtualbox.org

I tried upgrading to VirtualBox 5.1, which completed OK, but when I go to actually launch it (from command line), it says:
(I think it is a bit more formatted, though, in the actual rendition, iIRC.)

The host platform is EL 6 (Scientific, to be exact). Apparently, I have qt3 or so, and it looks like VBox 5.1 needs qt5? I looked around, and it seems EL6 does not have support for qt5.

Just FYI, I rolled back to 5.0, and it appears to be working OK. I've been using 5.0 for many weeks without much issue (though my Mageia no longer works, but that's a different issue).

Thank you for assistance.

HarryMan wrote:Apparently, I have qt3 or so, and it looks like VBox 5.1 needs qt5?

That would be absolutely true. VirtualBox 5.1 and later will require QT5. Take a look at the release notes for 5.1, where they state "GUI: overall migration to Qt5 (bug #11775)".

HarryMan wrote:it seems EL6 does not have support for qt5.

In that case I would stick to the 5.0.x series, until EL6 gets an update to its QT libraries.

You can always install from source. https://wiki.qt.io/How_to_Install_Qt_5_ ... n_CentOS_6

I have exactly the same error, but I run on Ubuntu 14.04.4 LTS, which should be officially supported. Deb package comes with the built-in libraries qt5, but it works only with the following command: I note that only runs using sudo.