Serious Bug: Under Performance Tab of BackOffice, Checked Cache Enable Radio, then All Pages Disappeared for 1.4.0.2

[Mav]

Under Performance Tab of BackOffice, Checked Cache Enable Radio, then All Pages Disappeared for 1.4.0.2 both for frontend and backend.

I changed /config/setting.inc.php back

define('_PS_CACHE_ENABLED_', '0');

but still not working.

Need urgent help, please.

Thanks.

[Mav]

I copied backup /config/ directory to recover damaged working /config/, then it works again.

[rocky]

This occurs when you try to enable memcache when it isn't installed on your server. PrestaShop v1.4.0.3 has a warning message that warns you when memcache isn't installed.