[Plugin: WordPress SEO by Yoast] error notice

do not know where to download it, i have tried to search for "wordpress seo plugin" "development version" with no success

thx, i am blind

this error notice is gone, but another appears – just after adding new taxonomy item to menu (not yet saving)

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘wpseo_maybe_upgrade’ was given in /var/www/vhosts/money.cz/httpdocs/wp-includes/plugin.php on line 405