Error Message upon opening

[Anonymous]

I am receiving the following error message when opening a file in Archicad 13.

Sources of the following Drawings are missing or they are in legacy format.
To make these drawings updateable, please
-Relink the missing sources to their current location
-Open legacy sources using the current version of ArchiCAD and resave them.

Does anyone know how to correct this? Without fixing it, it is going back to an old version of this file, not showing anything that was saved.
HELP!!

I don't know where/how to find anything legacy or linked?

[Karl Ottenstein]

You might start by opening Drawing Manager and looking at the missing drawings (flagged by icon) to see what path ArchiCAD is using to look for them. If the drawings are supposed to correspond to views in the current file, then just relink. If they are to a known external file, then do as the message suggests and update the external file to the current AC version (open and save, perhaps with a new name) and relink those drawings to the now-updated external file.

HTH,
Karl