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Common API Errors and How to Fix Them

(Amazon SP-API, Walmart DSV/MPA, eBay Trading/REST APIs)

When integrating with marketplaces like Amazon, Walmart, and eBay via APIs, you’ll inevitably encounter errors. These can break sync, halt order routing, or result in listing failures—leading to lost revenue and account risk if left unresolved.

This article covers the most common API errors, their causes, and actionable solutions—especially for users leveraging platforms like EcomBiz.AI for multichannel automation.

🔧 1. Authentication and Authorization Errors

Error Example:

pgsqlCopyEdit401 Unauthorized / Access Denied

Causes:

  • Expired API token or session
  • Improper client credentials
  • Missing required scopes or permissions

Fix:

  • Re-authenticate using your refresh token (OAuth)
  • Ensure your app has the necessary permissions for the requested endpoint
  • Double-check your credentials (client ID, secret, tokens)

🧭 2. Invalid SKU or Listing Reference

Error Example:

objectivecCopyEdit404 Not Found – SKU does not exist

Causes:

  • SKU not found in the target marketplace
  • Product not created before calling update/patch
  • Mismatch between local SKU and channel SKU

Fix:

  • Use GET calls to confirm listing existence before modifying
  • Ensure product creation flow is executed prior to update
  • Use mapping tools in EcomBiz.AI to align SKU references

🧾 3. Data Validation Errors

Error Example:

cssCopyEdit400 Bad Request – Invalid value in request body

Causes:

  • Required fields are missing (e.g., product title, price)
  • Incorrect attribute values (e.g., wrong format, unsupported characters)
  • Exceeding character limits

Fix:

  • Review API documentation for field-level validation
  • Use field sanitization and validation in your listing tool
  • Log full response body to pinpoint the faulty field

⛔ 4. Rate Limit Exceeded

Error Example:

CopyEdit429 Too Many Requests

Causes:

  • Too many requests in a short time
  • Bulk operations exceeding allowed limits

Fix:

  • Implement request throttling and exponential backoff logic
  • Use batch endpoints where supported (e.g., Amazon Listings Feeds)
  • Monitor usage against marketplace rate limits (visible in developer dashboards)

📦 5. Inventory Sync Failures

Error Example:

javascriptCopyEditError updating quantity – Invalid warehouse ID

Causes:

  • Warehouse or fulfillment node not configured
  • SKU not mapped to correct fulfillment center
  • Attempting to update quantity on inactive SKUs

Fix:

  • Register warehouses in marketplace settings
  • Ensure SKU is live and published
  • Use EcomBiz.AI inventory tools to auto-link SKUs to their fulfillment sources

🚚 6. Order Submission Failures

Error Example:

sqlCopyEditOrder payload rejected – Missing shipping method

Causes:

  • Incorrect or missing logistics info (carrier, method)
  • SKU not enabled for fulfillment
  • Customer address validation errors

Fix:

  • Validate order data before submission (especially address + method)
  • Set fallback carriers/methods in your automation platform
  • Auto-flag failed orders for manual review via dashboard

🔁 7. Duplicate Submission or Request Conflicts

Error Example:

pgsqlCopyEdit409 Conflict – Duplicate request

Causes:

  • Multiple attempts to submit same feed/order
  • Simultaneous update requests to same SKU or order

Fix:

  • Implement idempotency keys if supported
  • Avoid reprocessing orders unless explicitly needed
  • Add delay between update attempts for the same record

🧠 8. Misconfigured Webhooks or Callbacks

Error Example:

pgsqlCopyEdit500 Internal Server Error on callback URL

Causes:

  • Receiving endpoint (your server) is down
  • Payload format not expected by your webhook handler
  • SSL certificate issues

Fix:

  • Ensure endpoint is HTTPS and always available
  • Log incoming payloads and verify your parser matches structure
  • Use a service like RequestBin to test payloads

🧩 Marketplace-Specific Quirks

Amazon SP-API:

  • Requires role-based scopes and developer account whitelisting
  • Feeds are preferred for large updates (over real-time endpoints)

Walmart Marketplace API:

  • Fulfillment node setup is mandatory for inventory sync
  • Shipping templates must be created and assigned to products

eBay Trading/REST APIs:

  • Must enable the correct version (Trading vs. REST for listings vs. orders)
  • Policies (payment, return, shipping) must be attached before listing

🔄 How EcomBiz.AI Handles These Automatically

EcomBiz.AI includes built-in features to minimize API errors:

  • Auto Token Refreshing
    So your sessions never expire unexpectedly
  • Smart SKU Mapping
    Ensures accurate linkages between your products and the marketplaces
  • Error Logging & Retry Queue
    Failed submissions are logged and retried with exponential backoff
  • Validation Engine
    Prevents malformed payloads from being submitted

Final Thoughts

API errors are inevitable, but manageable. With proper validation, logging, retry logic, and automation tools like EcomBiz.AI, you can keep your multichannel operations running smoothly—even at scale.

Proactive error handling = more uptime, better seller metrics, and fewer headaches.

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