sites/all/modules/contrib/memcache/database.inc

I think this was fixed in 6.x-1.10, but please re-open if you are still seeing it.

Just upgraded from 6.x-1.9 to 6.x-1.10. Still seeing it:

PHP Fatal error: Call to undefined function db_fetch_object() in /mnt/www/html/pega2stg/docroot/sites/all/modules/contrib/memcache/database.inc on line 37 request_id="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

settings.php contains:

$conf['cache_inc'] = './sites/all/modules/contrib/authcache/authcache.inc';
$conf['cache_inc_via_authcache'] = './sites/all/modules/contrib/memcache/memcache.inc';
$conf['memcache_bins'] = array(
'cache' => 'database', // memcache on value: default
'cache_block' => 'database', // memcache on value: default
'cache_content' => 'database', // memcache on value: default
'cache_filter' => 'database', // memcache on value: default
'cache_form' => 'database',
'cache_menu' => 'database', // memcache on value: default
'cache_page' => 'database',
'cache_update' => 'database', // memcache on value: default
'cache_views' => 'database' // memcache on value: default
);