Value of end not valid rule for attributes or attribute parents
The error is caused because the item is a variation attribute (child) or has attributes (parent), and the availability was set to "Always Available - Disable when Unavailable." This can be caused because it was selected or because the the default for "Out of Stock Rule Default" rule is set to "End" in Settings>Storefront>Product Pages
Variation listings may not have this availability Rule on the storefront.
To fix: Change the Availability for the parent and the child items in the variation to "Inventory Controlled - Always Display" - which will display variants as "Out of Stock" when they reach 0 Stock.
Note: This translates into Rule:Update instead of Rule:End in bulk