So you invested your time into xbim v3 and we broke your code. Sorry for that. We believe you will like all the goodies coming with xbim v4 (like ability to work with IFC2x3 like if it was IFC4). To learn more about what is new in xbim v4 read this. If you already have an idea about what has happened in xbim and you just want simple guidelines for fast upgrade here is how we did it most of the refactoring of our own code depending on Xbim Essentials:
usingstatements referring to IFC. Change names of all classes from
Xbim.Ifc4.xxxnamespaces. Make sure you don't reference IFC2x3 namespaces. There are interfaces as well but these won't work for IFC4.
Xbim.Ifc2x3.dlland make sure your solution doesn't complain about missing references in using statements. Put it back than.
IfcStore. It should have most of the functions you were used to in
XbimModelbut can use all combinations of storage, IFC versions and physical formats.