If you use WordPress 2.5 or (gasp) earlier, you may encounter an error message “Call To Undefined Function: ctype_digit()” when you try to upload and attach an image to your post from inside the post editor.
More specifically, the bug will be something along the lines of :
PHP Fatal Error: Call to undefined function: ctype_digit() in /wordpress/wp-includes/link-template.php …
This is a known bug in WP 2.5, and obviously the most relevant solution is to upgrade to WordPress 2.6 which at this point is the latest stable release.
If you can’t upgrade for whatever reason (laziness doesn’t count) then you should be able to fix the image or photo upload issue by downloading a fresh copy of the link-template.php file which contains the bug fix for the ctype_digit() error. That preceding link, by the way, is to the file from the official WordPress file download link … that being said, always make sure you have a full backup available!
