unit_pricing_measure / unit_pricing_base_measure unit must be a supported weight, volume, length, area, or per-unit measure. Free-text units are rejected.
Microsoft Merchant Center's product schema has format and value rules per attribute. This issue is typically: missing a required attribute for the category, an invalid enum value (e.g., 'XL' submitted where 'M, L, XL' is the valid set), out-of-range numbers, or attributes that conflict across the feed.