[woocommerce] too many redirects after updating to 2.6.x

Hi, I need help. After updating woocommerce from version 2.5.x to 2.6.6, my site can’t be opened (crashed). The error reads

“(example.com) redirected you too many times”
Try clearing your cookies
ERR_TOO_MANY_REDIRECTS

disabled the plugin, voila, popped back up. Oddly, my site used to be on https:// on all page except on woocommerce checkout page. But after this error, with woocommerce disabled, my homepage redirects to https:// . but I need my woocommerce to run, otherwise there’s no store.

How can I fix this?
1/ the error woocommerce made
2/ the https:// redirect

* i’m using wordpress multisite (yes, I have configured the multisite settings on wp-config)
* the wordpress and site address both are on https:// before I converted to multisite
* i’m using Zerif Lite Theme, version 1.8.4.9, with child theme.