Can not Edit Orders and Products

As anyone else in this forum, I’ve updated Woocommerce to the latest version, 3.0.

And suddently it turns into a nightmare, -_-.
I can’t event open products page. Any previous order can’t be opended for editing.
Event product page in the frontend is loading slower than before.

But, it does throw an error like below.

[05-Apr-2017 06:07:47 UTC] PHP Notice: woocommerce_get_page_id is <strong>deprecated</strong> since version 3.0! Use wc_get_page_id instead. in /home/u7480820/public_html/wp-includes/functions.php on line 3829

Anyone please help me.
I would really appreciate.
Thanks in advance