Re: Sign up fatal error!
Network Parent Theme sounds like a custom, 3rd-party theme to me. The default parent/child BP themes are bp-sn-parent and bp-default.
Make sure that you have enabled the BuddyPress default theme in the â€œSite Admin > Themesâ€ menu and then activated the BuddyPress default theme in â€œAppearance > Themesâ€.
If you’re still having issues, read the second linked to thread in my post above.