Unrecoverable error repeating

Maybe one or more of the shapes are corrupt in some way. Maybe if you do an ‘optimize’ of each shape if will help. Or compact them.

On a side note, generally I recommend to NOT merge shapes, because they are so hard to ‘unmerge’ if you decide to make changes.

Error message 30009 received after attempting to merge roof panel with main body of building. Using 3DC Plus edition.. usually allows me to recover after exiting. Not this time. Any suggestions greatly appreciated to avoid doing over.