It looks like when a new attribute is added to a product that has some variants, Odoo may WIPE OUT all existing variants and recreate them!This means all inventory data, relation to any BOM, etc. are deleted for good!
It happens when Odoo can not figure out what should happen to existing variants when a new attribute is added and AT THE SAME TIME user is providing more than one value for the new attribute. This only happens if the new attribute's setting for "Variant Creation Mode" is set to "Instantly" which is the default setting by the way and something that can not be changed later.
Wiping out data without warning can lead to unexpected loss of data. Is there a way to stop Odoo from deleting and issue an error instead? or at least issue warnings when this is about to happen ?
I just confirmed this also the case in Odoo 17.0
Experimenting more with adding/deleting attributes from a product I found out Odoo actually unlinks existing variants from the product instead of deleting them as initially indicated in my post. It archives them. They stay in sale orders where they were used.
This is still not good we end up with duplicates and all reports will show the old archived variants and the one Odoo created in their place show up as separate products.
Yes, it's not ideal. The "old" variants are archived, as you say, and you would have to do an inventory adjustment to put any stock back to the "new" variant. The archived variants cannot be selected on sales orders (etc.) but it can certainly cause confusion. https://odootricks.tips/using-variants-colour-size-fit/
Facing the same problem. Any solution?