Make sure that the developer account you use in Xcode has an "Apple Distribution Certificate" on your computer by following these steps:
- Accept all developer agreements by signing in to your account at https://developer.apple.com first as others have suggested
- Start Xcode and select "Settings..." from the Xcode menu
- Select the "Accounts" tab
- Select the Apple ID you want to use on the left pane (or add it if you don't already have it listed)
- Select the Team you want to use for distribution on the right pane (this would usually be your company/business name or your own name I guess if you're not incorporated)
- Click the "Manage Certificates..." button
- If you don't see an Apple Distribution certificate, click the + button on the bottom left corner, and select Apple Distribution
Doing these steps fixed the crash issue for me and I was finally able to make a new release.