Amazon Error 100339: How to Fix HTML and Code Markup in Your Product Listings
Error 100339 occurs when Amazon detects HTML, JavaScript, CSS, or other code markup in product listing attributes. Sellers must remove all non-plain-text formatting from titles, bullet points, descriptions, and keywords to resolve it.
Overview
Error 100339 is a feed processing error that Amazon triggers when it detects HTML tags, JavaScript, CSS, or other code markup embedded within your product listing attributes. This is a common issue that can prevent your listings from going live or updating properly, and it frequently catches sellers off guard — especially those who copy and paste content from websites or word processors into their product detail fields.
Key Points / What Sellers Need to Know
- Plain text only — Amazon requires all product detail page content to be submitted in plain text format, with no HTML, JavaScript, CSS, or any other type of code markup.
- Common culprits — HTML tags like
<p>,<br>,<b>,<i>, and<strong>are the most frequent triggers for this error, often introduced through copy-paste workflows. - Affects multiple fields — The error can be triggered by code found in titles, bullet points, descriptions, generic keywords, or any other product attribute field.
- Hidden formatting is a risk — Even if you didn't intentionally add code, pasting content from a website, email client, or rich text editor can silently introduce markup that triggers this error.
- Check your feed report — Amazon's feed processing summary report will identify the specific attribute that contains the offending markup, helping you pinpoint exactly where to make corrections.
Why This Error Occurs
Amazon enforces strict content formatting standards across its product catalog to ensure a consistent shopping experience. When sellers submit product data through feeds — whether via flat files, the API, or third-party tools — Amazon's systems scan every attribute field for non-compliant content. Error 100339 fires when the system detects anything that resembles code rather than plain product information. This includes obvious HTML tags, but also less apparent issues like special Unicode characters, CSS styling fragments, or JavaScript snippets that may have been inadvertently embedded. Sellers who manage large catalogs or use content management systems to generate their listings are particularly susceptible, since automated workflows can introduce formatting artifacts that are invisible in a standard text editor but clearly detectable by Amazon's validation engine.
Analysis & Recommendations
Why This Matters
This error can block new listings from going live and prevent updates to existing products. Sellers who rely on feed-based catalog management need to understand how to quickly identify and fix markup issues to avoid operational delays.
Key Takeaways
- Amazon requires all product detail page content to be plain text — no HTML, JavaScript, or CSS allowed
- Copy-pasting from websites or rich text editors is the most common way code markup gets introduced
- Your feed processing summary report will tell you exactly which attribute triggered the error
- Using a plain text editor as an intermediate step when preparing listing content prevents most occurrences
Recommended Actions
- →Review your feed processing summary report to identify the specific attributes flagged with Error 100339 and strip all HTML tags
- →Establish a workflow of pasting content through a plain text editor before entering it into listing files or tools
- →Audit any third-party listing tools or feed templates you use to ensure they are not injecting markup into your product data
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