As a followup to my other question, I'm continuing to have issues submitting my iOS 8 app (which includes a Sharing Extension and a framework target). On a submission attempt I receive the above error message. Others with my issue (as pointed out in the afore-linked question) have the same issue, but resolved it in ways that aren't relevant to my case.
The error message implicates my Sharing Extension target, which links to a framework that I wrote, which is shared between the Extension and the app. I'm pretty sure Apple was clear that I'm allowed to use frameworks in Extension targets (in fact, it's preferred!). So what other causes might there be for this error?