A view said a column no longer exists, or is not set up for me

The view was saved while that column was showing. "No longer exists" means it has gone since: usually a custom field that was switched off in Custom fields, or cost of goods turned off in WooCommerce. "Not set up for you" means the column is still there for the person who shared the view, but custom-field and taxonomy columns are chosen by each person and you have not switched that one on. Either way the view opens without it and names it, and it still remembers the column. Switch the field on in Custom fields (or the taxonomy in Taxonomies), then open the view again from Views, and the column comes back. Do not save the view again before that, or it is saved without the column. A category, tag or attribute value deleted since the view was saved is left out of the filter, and the rest of the filter still applies.