Check all the activities, but there are a bunch or warnings as we need to use js functions instead of "on***" functions:
qrc:/gcompris/src/core/Bonus.qml:75:5: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... }
Also, parameters needs to be explicitely declared:
qt.qml.context: qrc:/gcompris/src/core/ActivityBase.qml:192:5 Parameter "dialog" is not declared. Injection of parameters into signal handlers is deprecated. Use JavaScript functions with formal parameters instead.