vB root/includes/functions.php error

Warning: Invalid argument supplied for foreach() in [path]/includes/functions.php on line 5066

PHP case sensitivity

I’ve always found the case sensitivity rules in PHP a little mysterious, and also a little hard to find definitive information on. So, for reference sake here they are. Tests based on PHP 5.3 running on Mac OS X:
Case sensitive (both user defined and PHP defined)

variables
constants
array keys
class properties
class constants

Case insensitive (both user defined and PHP defined)

functions
class constructors
class methods
keywords and constructs (if, else, null, foreach, echo etc.)

source:http://the-echoplex.net/log/php-case-sensitivity