Some people believe that they should copy the sample config to the "real" config. I noticed this several times in IRC and on the bugtracker.
I guess this warning should be enough to avoid this in the future.
<?php
+/**
+ * This configuration file is only provided to document the different configuration options and their usage.
+ * DO NOT COMPLETELY BASE YOUR CONFIGURATION FILE ON THIS SAMPLE. THIS MAY BREAK YOUR INSTANCE.
+ * Instead copy configurations switches that you consider important for your instance manually to your configuration.
+ */
+
/* Only enable this for local development and not in productive environments */
/* This will disable the minifier and outputs some additional debug informations */
define("DEBUG", true);