Overview

Error 100408 is a listing attribute validation error that Amazon triggers when it detects incorrect or improperly formatted values in your product listing fields. When this error fires, Amazon suppresses the problematic attribute value, which can result in incomplete or inaccurate product detail pages that hurt discoverability and conversions.

Key Points / What Sellers Need to Know

• Attribute values get suppressed, not just flagged — When Amazon detects an incorrect attribute value, it removes that data from your listing entirely rather than simply warning you. This means your listing may be missing critical details like size, material, or other specifications that shoppers rely on.
• Format mismatches are a common trigger — Using non-standard formats such as "XXL" instead of the accepted "2XL" for sizing will cause this error. Each category has specific formatting expectations.
• Inaccurate product information triggers suppression — Describing a cotton shirt as "100% silk" or applying shoe sizing conventions to clothing items will result in Amazon flagging the attribute as incorrect.
• Special characters and promotional text are not allowed — Inserting symbols, special characters, or marketing language into attribute fields that expect factual product data will cause this error.
• Category-specific rules apply — What works in one product category may not be valid in another. Size formats, material descriptions, and other attribute values must align with the specific category your product is listed under.

Common Causes

This error surfaces for several distinct reasons, and understanding which one applies to your situation is the first step toward resolution. The most frequent cause is a simple format mismatch — you entered a value that Amazon recognizes as roughly correct but not in the exact format the system expects. For example, clothing size fields typically require standardized values like S, M, L, XL, or 2XL, and deviating from that convention will trigger suppression. Another common scenario involves cross-category confusion, such as using shoe sizing conventions on a clothing listing or applying electronics specifications to home goods. Amazon's catalog system validates attribute values against category-specific rules, and mismatches between your data and those rules will be caught.