More info on exactly what you're doing would help.
Hi! On my old Mac OSX version 10.4.11, I opened my indesign 2.0 document and packaged it, so it would save it with fonts and artwork to my desktop. I then moved it into a sharing folder. I can't get migration assistant to work, probably because of the age of my old computer, so I opened up the network and got my new iMac to bring the document over. I can open it and view it, but It won't save the document. Do you have any suggestions?
I'm not sure how you're moving those packages but that could be a cause of
the problem. Try using Dropbox to share the folders between to the two
Do you have writing permission on that folder?
I would try to open and to save on a local folder and then package again with the new version. Open the package, save the new file at the same place as IDML, open that IDML and save again as INDD and check what might have changed and do all need repairs to that file.