bad update 1.5.2.1

i can’t even install Yoast SEO. I get this:

Fatal error: Cannot use object of type WP_Error as array in /var/www/html/www.bestpalosverdeshomes.com/wp-content/plugins/wordpress-seo/inc/wpseo-non-ajax-functions.php on line 44

@vanderelbe Interesting. No clue how changing the language could affect the plugin in that way. I’d like to find out though. Could you check if there are any PHP errors when on German which aren’t there when you switch to English ?

@jrf thank you for your answer.
how can I check the PHP errors / where do I find them ?

@vanderelbe – You can find instructions about turning on error logging with backtraces here: https://gist.github.com/jrfnl/5925642

Oh and FYI: just turning WP_DEBUG on will *not* show all errors, turning error logging on as explained in the gist *will*.