you did nothing wrong except imagining that you could easily auto upgrade your wp site without first scanning the forums and support help on this issue. You would have learned it was extremely risky! Folly perhaps. There are many posts on this problem with as many solutions.
Here was my first post on my problem – with some solutions suggested:
http://ww.wp.xz.cn/support/topic/upgrading-to-wp-311-problem?replies=3
Here is another:
http://ww.wp.xz.cn/support/topic/php-fatal-error-call-to-undefined-function-is_network_admin?replies=3
I hope you backed up your site aND database before attempting to upgrade.
Good luck with successfully resurrecting your site – I am still struggling.
Curt
