Here’s a quick heads up for those of you who encounter this error when you upgrade your wordpress (especially for those who upgrade to WordPress 2.3.1). If you see this error after replacing the old wordpress files with the new ones:

Call to undefined function: _make_cat_compat() in /home/hongkiat/public/blog/wp-includes/category-template.php

Solutions

This is probably caused by the file category-template.php. Try re-upload the category-template.php file, and it should be fine.