I just updated WordPress to the latest version, 4.0, and I had a bad surprise - timthumb stopped working. the thumbnails are not generated. I cleared theme's cache folder, and checked to see if chmod is 755 - it is. timthumb is also updated to the latest version. this is how I call the thumbnail
<img src="<?php bloginfo('stylesheet_directory'); ?>/timthumb.php?src=<?php get_image_url(); ?>&h=170&w=170&zc=1" alt="<?php the_title(); ?>"/>
What else can I do?