Thank you for the post.
I found this documented in the help file under Importing Bento data (Mac OS):
"Before you begin importing Bento data, be sure that the bento.bentodb file is in its default location in your home folder: Library/Application Support/Bento."
If the bento.bentodb file is located in another location other than the default, try moving the file back to the default location and importing again.
FileMaker has also released a Migration Tool from Bento 4 to FileMaker Pro 12. It converts your existing Bento 4 for Mac data (including the contents of media fields and form designs) into a FileMaker Pro 12 database. There are some limitations so please review the Bento 4 to FileMaker Pro Migration Tool PDF prior to migrating. More information can be found here:
Is FileMaker Pro right for you?
I'm having the same problem, tho I'm migrating directly from Bento 4.1.2 on my MacBook Pro to FileMaker Pro 12. I get the same warning (pop-up box appears three times, each time i click ok) saying that "The document 'XX' could not be opened, FileMaker Pro cannot open files in the 'Filemaker Document' format", even after the Migration Tool tells me it was successful. Yet when I open the FP file indeed some of the database has transferred over, but only a small fraction of it. My Bento database is in its default location.
Thank you for your post.
Are you migrating all of the Libraries from Bento? Only a few? Does the Migration complete successfully? Assuming the migration is successful and you still cannot open the resulting .fmp12 file, I'd like to see your bento.bentodb file to determine why it is failing. Check your Inbox at the top of this page for instructions where to send your bento.bentodb file.