When updating product stock quantity I get the following error message:

The operation cannot be completed, probably due to the following:- deletion: you may be trying to delete a record while other records still reference it- creation/update: a mandatory field is not correctly set[object with reference: weight_uom_id - weight.uom.id] It was working at one time but I must have changed something to mess it up. I think its a configuration setting but have no clue what.

Odoo version is 8.0-20151126

Thanks