I just updated the plugin to 1.6.4 from 1.6.2, but it wasn't able to get activated:
Fatal error: Class 'autoptimizeConfig' not found in /home/.../public_html/.../wp-content/plugins/autoptimize/autoptimize.php on line 25
and I omitted the line 25:
// Initialize the cache at least once
$conf = autoptimizeConfig::instance();
then it happened:
Fatal error: .../plugins/autoptimize/autoptimize.php on line 37
and I deleted the line 37:
// Do we gzip when caching?
define('AUTOPTIMIZE_CACHE_NOGZIP',(bool) $conf->get('autoptimize_cache_nogzip'));
so it occurred:
Fatal error: .../plugins/autoptimize/autoptimize.php on line 151
surely I didn't cleanse the line 151, because it was a call to CDN configuration; I DECIDED TO DOWNGRADE THE VERSION ;)