Overview

Amazon sellers encounter error 18031 when they submit order‑adjustment feeds that contain invalid amounts. The system blocks the request if the adjustment is zero or if it exceeds the remaining balance on the order line. The error appears in Seller Central and through the SP‑API, and it can halt bulk refunds, concessions, or other financial corrections. Understanding why the error occurs and how to correct it is essential for keeping cash‑flow and customer‑service processes on schedule.

Key Points

• Zero‑value adjustments are rejected — Amazon only accepts adjustment amounts greater than 0; a feed line that tries to credit $0.00 will be denied instantly.
• Amounts larger than the open balance are blocked — If an order line shows $12.34 remaining and the feed requests $15.00, the system returns error 18031.
• Resubmitting the entire file creates duplicates — Uploading a feed that still contains rows already processed successfully causes the system to treat those rows as new adjustments, which now have a zero balance and trigger the error.
• Outstanding balances are viewable in Seller Central — The “Order Details” page lists the current refundable amount for each SKU, letting sellers confirm the correct figure before building a feed.
• Bulk‑feed users are most vulnerable — Because each line is evaluated independently, a single mis‑calculated row can cause the whole file to be rejected or generate multiple error 18031 entries.
• Error 18031 does not affect account health — The issue is limited to the specific adjustment request; it does not generate performance warnings but can delay refunds.

How to Fix Error 18031

1. Confirm the remaining balance — Open the order in Seller Central, locate the line item, and note the “Refundable Amount.”
   • Example: Order #112‑334‑556 shows a remaining balance of $8.25 for ASIN B07XYZ.
2. Adjust the feed amount — Edit the XML or flat‑file row so the “AdjustmentAmount” field matches a value greater than 0 and less than or equal to the refundable amount.