Hi,
Am I right that you tried to import file(s) which has .archive extension?
If yes:
As a workaround, modify the extension to .BIMProject20 (if you use version 20), or .BIMProject19 (in case of version 19), make sure to use the same format (capital and small letters) then try the import process again.
Regards,
Istvan
István Moharos
Manager, Technical Services
GRAPHISOFT