I've gotten the same errors recently trying to run Calibre remotely (start an X server on one box, ssh into another box with X forwarding enabled, and run Calibre on the remote box). This suggests a possible Qt bug:
https://bugreports.qt.io/browse/QTCREATORBUG-14427
If I invoke Calibre with the following:
Code:
QT_DEVICE_PIXEL_RATIO=1 nohup calibre &
it fires up and runs like it should.
(The remote system is Gentoo Linux. The local system is Windows 7 SP1 with Cygwin.)