What happens when you open a local copy of the file, save a copy as..., then try that copy with 9?
You could also open the privs on the v8 copy, and open...make a small change...and then resave it, maybe just 'reblessing' the privs would work....
Thanks for posting.
You can certainly try mwc's suggestion of saving a copy (although I would add that you try a compact copy) and seeing if this helps. In most cases, though, this is the sign of a damaged/corrupt file. It opens successfully in FMS 8 b/c FMS 9 is more advanced in detection and includes the benefit of the consistency check. Even if you decided to stay on FMS 8, I would recommend recovery maintenance of your file as there is most likely something wrong.
One thing you can do is File > Save a Copy as > Clone in your FMP 8 application (you can even compact and/or recover the clone if you want to). Try opening the Clone in the FMP 9 application. If everything is ok, I would recommend importing the data from the original file into the Clone. If you get the same error message, then we can assume there is an issue with the file (bad layout, object, script, etc.)
Do you have any working backups? If so, you could create a clone of that file and import the updated data.
Let me know how it works out.