For some reason, when I upgraded one of my authored plugins Slimbox2 Slideshow, I got an error with this plugin
"Call to undefined function get_currentuserinfo()"
On line 552, "get_currentuserinfo();"
the fix is a simple
require(ABSPATH . WPINC . '/pluggable.php');
prior to this line, though I don't know the root cause of this error, as I had never experienced it prior.
It could very well be something to do with my plugin