I also needed an answer here and researched it so much that I reviewed the sources. The trick is here "/Projections/defaultBehaviour", in QGis3 they decided to change it to "/Projections/defaultBehavior" (behavioUr -> behavior). yw -- Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-Developer-f4099106.html