function bp_members_invitations_get_modified_registration_disabled_message() {
	$message = '';
	if ( bp_get_members_invitations_allowed() ) {

		$invite = bp_get_members_invitation_from_request();
		if ( ! $invite->id || ! $invite->invitee_email ) {
			return $message;
		}

		// Check if the user is already a site member.
		$maybe_user = get_user_by( 'email', $invite->invitee_email );

		if ( ! $maybe_user ) {
			$message_parts = array( esc_html__( 'Member registration is allowed by invitation only.', 'buddypress' ) );

			// Is the user trying to accept an invitation but something is wrong?
			if ( ! empty( $_GET['inv'] ) ) {
				$message_parts[] = esc_html__( 'It looks like there is a problem with your invitation. Please try again.', 'buddypress' );
			}

			$message = implode( ' ', $message_parts );
		} else if ( 'nouveau' === bp_get_theme_package_id() ) {
			$message = sprintf(
				/* translators: 1: The log in link `<a href="login_url">log in</a>`. 2: The lost password link `<a href="lost_password_url">log in</a>` */
				esc_html__( 'Welcome! You are already a member of this site. Please %1$s to continue. If you have forgotten your password, you can %2$s.', 'buddypress' ),
				sprintf(
					'<a href="%1$s">%2$s</a>',
					esc_url( wp_login_url( bp_get_root_domain() ) ),
					esc_html__( 'log in', 'buddypress' )
				),
				sprintf(
					'<a href="%1$s">%2$s</a>',
					esc_url( wp_lostpassword_url( bp_get_root_domain() ) ),
					esc_html__( 'reset it', 'buddypress' )
				)
			);
		}
	}

	return $message;
}