In one of the WP installations I updated today (2.3.2 -> 2.3.3), I found a wp-content/cache folder which I deleted - according to the upgrading instructions
...wp-content folder; Special Exception: the wp-content/cache and the wp-content/plugins/widgets folders should be deleted.
This folder was non-existing in the first update i did.
Now, after running the upgrade script on this second installation, I got a 500 internal server error message, saying
Warning: fopen(/web/htdocs/www.infocusfoto.it/home/wordpress/wp-content/cache/wp_cache_mutex.lock) [function.fopen]: failed to open stream: No such file or directory in /web/htdocs/www.infocusfoto.it/home/wordpress/wp-content/plugins/wp-cache/wp-cache-phase2.php on line 96
In other words, WP missed the cache folder that I deliberately deleted.
My question is if this is a mistake in the upgrade instruction or if I just made some mistake myself.
(Everything works as it should after I uploaded the missing folder from a backup.)
PS site: http://www.infocusfoto.it (work in progress...)