[Duffers]

I got the same, although oddly only one mac, not both. I got the following reply from the ninjas:

- Log into your iDisk, and clear it of any OmniFocus files (perhaps moving them to the Desktop in case you need them later)

- Run a sync on the "good" copy of OmniFocus (that is, the Mac that isn't returning an error when you try to launch OmniFocus). This should copy that copy of the database onto your iDisk.

- Quit OmniFocus on the Mac that won't open the database.

- Navigate to ~/Library/Application Support/, and move the file OmniFocus.ofocus aside to the Desktop.

- Now, relaunch OmniFocus- you'll notice that it opens with the blank "welcome" document.

- Run a sync- if it asks you to pick the local or server copy, pick the server. This should copy the database on your sync server to the Mac.

- Relaunch OmniFocus, and you shouldn't see that error message again.

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can't comment if this worked as didn't follow instructions accurately. Uninstalled and re-installed OF in the meantime. Initially has worked.