Fatal error: Call to undefined function

Published in

Problem

Well, the title says it all. Very common.

Solution 

http://drupal.org/node/175807#comment-790323
Replace the function name with whatever name in your case is the culprit, so:
if(function_exists('whatever')) {
<--The piece you don't want to run if the function doesn't exist-->
}


Not very elegant, but effective. A real solution is case specific and a bit deeper, but, eeh, who cares? It gets you out of shit for now.