All your plugins are off, I’m assuming. Switch to the default theme, Twenty Thirteen.
If that doesn’t work, reinstall WP core.
I came across this too.
Call to undefined function wp_get_current_user()
I network deactivated like 4 plugins, which I didn’t want used by all of the other sites in the multisite network (3 total). Then I went into the root site and activated one of those plugins (easy coming soon) enabled it and saved it…and now I’ve run into this problem.
If I rename the plugins folder, I can get access to the admin. If not, I get the error.
I fixed it….
Do you have Multisite Plugin Manager installed?
Try to disable it via FTP…maybe it will work.
Check this post out:
http://ww.wp.xz.cn/support/topic/php-fatal-error-call-to-undefined-function-wp_get_current_user?replies=11#post-5076381
This is why we tell you to deactivate ALL plugins.
Yes it sucks. I know :/ But when this happens, it’s how we debug.
Alternatly, of course, you could install a localhost instance with all your plugins and theme and see if you can reproduce it.
