Hi from France.
I just encountered the issue and had to roll back to WooCommerce 2.0.20 and my yesterday last database backup. If you upgrade to WooCommerce 2.1.2 while your website is using Woothemes MyStile v.1.2.7, you will have the following fatal error :
Fatal error: Call to undefined method WooCommerce::mfunc_wrapper() in [...]
The error is related to this code line :
49 > $woocommerce->mfunc_wrapper( 'woocommerce_cart_link()', 'woocommerce_cart_link', '' );
I'm actually searching if the actual version of the MyStile theme available here :
... has been updated for Woocommerce 2.1.2.