I'm trying to run some example projects from GitHub. After upgrading to Xcode 8, I see the same set of errors for multiple projects:
None of your accounts are a member of '...': An unexpected error occurred. Xcode cannot find a team matching '...'.
No profiles for '...' were found: Xcode couldn't find a provisioning profile matching '...'.
Code signing is required for product type 'Application' in SDK 'iOS 10.0'
I've tried the steps described here: https://stackoverflow.com/a/39498874/2901178, but it didn't work.
If you found any Extensions under TARGETS. You have to choose the development team for that too. Hope this helps you.