Can't export to rhino v4 format

recently when I try to export simple geometry I get a message “this model contains information that cannot be saved in the Rhino 4.0 file format”. For my workflow it is crucial to be able to export to rhino 4.0 format. It happened recently with all the other rhino files which could be exported to 4.0 version before. Is there any solution I could apply? I tried reinstalling Rhino, but it didn’t help. I’m on Rhino Mac 5.5.4 (latest version).

Thanks for your help.

That’s a pretty standard warning for backwards saving. Just ignore the warning and see if anything is actually missing V4. Usually it’s fine, except for data attached to plug-ins.