@SGaist I finally threw away my whole QT source folder and started once more from scratch and now the modules and libraries are back in sync as 5.6.1.

Marking this as solved. Thanks

Only advise I can give to everyone that runs into this as well is:
Check if your library and modules are in sync. They seem to have gotten out of sync for me after using git update or branch switch.

Hi and welcome to devnet,

Did you double check the that sudo apt-get install qtcreator ran successfully ?