I have a Magento 2 community edition installation that I am attempting to update via Composor.
When the upgrade is completed, icons on the front end and the back-end are missing, and I am unable to add products to the cart. I had run the following instructions which resolved the issue with the icons however not on add to cart:
When I switched to the Luma theme, everything seems to be working alright, however when I tried to make a new child theme, the issue once again persisted. After attemptimg to switch back and forth among themes and trying to clear the cache, even with the luma theme I was no longer able to add anything to the cart. I tried switching from server compilation mode to client mode and back, however Admin was no longer usable as it lost all of the CSS.