com_contacts uses the includes/vcard.class.php file, which also needs to be modified to avoid this error:
Fatal error: Cannot redeclare quoted_printable_encode() in includes/vcard.class.php on line 74
In vcard.class.php around line 36 is the function quoted_printable_encode. This ends up declaring twice, causing the error, so you can prevent the error and fix the error by checking if the function already exists, and if it does, PHP ignores the function declaration. Adding the green lines of code before and after the existing function clears the problem.
if(!function_exists('quoted_printable_encode')) {
function quoted_printable_encode($input, $line_max=76) {
/* ... */
}
}
source: http://www.kpsystems.com.au/fixing-joomla-10-for-php-53x.html
