PA-API v5 Requests Return 404 InternalFailure — Valid Associate Tag and Credentials

Question

I'm an Amazon Associate with a working and active affiliate account (I’ve had valid sales for some time), and I’m currently building a price comparison tool using the PA-API v5. However, I'm consistently receiving 404 errors with the following response:

json
Copy
{
  "__type":"com.amazon.coral.service#InternalFailure"
}

**My Setup:**

**Associate Tag:** Active and earning

**Access & Secret Keys:** Confirmed working and current

**Region:** webservices.amazon.com

**Partner Type:** Associates

**Partner Tag:** Matches my associate tag
Requests are signed using AWS Signature v4

Tested both through code and Amazon's Scratchpad

**Results:**
Scratchpad sometimes works, but not always. Real-world requests from my Flask app always return 404.

Response body is always:

json
Copy
{"__type":"com.amazon.coral.service#InternalFailure"}

**What I’ve Tried:** Rotating credentials

Validating all headers and payload structures
Using the correct marketplace and region
Checking documentation and FAQ

**What I’d Love Help With:**

What are the possible causes for this kind of persistent 404 with “InternalFailure”?
Could this be tied to usage caps, specific Associate Tag restrictions, or regional limits?
Is there any way to verify if my account is still authorized for PA-API access programmatically?
Any working example of a known-good, minimal JSON payload or curl request would also be super helpful.

Thanks in advance!

re:Post Agent · Answer

The issue you're experiencing with the PA-API v5 returning 404 errors and "InternalFailure" messages could be due to several factors. Here are some possible causes and suggestions:

1. Request throttling: The PA-API has strict rate limits. If you're making too many requests in a short period, you may be hitting these limits, resulting in errors. Consider implementing an exponential backoff strategy in your code to handle rate limiting. This involves increasing the delay between retries exponentially when you encounter errors.

2. API usage: Ensure you're not exceeding the allowed number of requests per second for the PA-API. Check your usage and adjust your request frequency if necessary.

3. Credentials and permissions: While you've confirmed your credentials are working, double-check that your IAM user or role has the necessary permissions to access the PA-API. Sometimes, permissions can be inadvertently changed or revoked.

4. Regional issues: Although you're using the correct endpoint (webservices.amazon.com), there could be regional restrictions or issues. Try using a region-specific endpoint if available.

5. Payload and request format: Ensure your request payload is correctly formatted and includes all required parameters. Even small discrepancies can lead to errors.

6. Service issues: Intermittent problems with Amazon's services could cause these errors. If the issue persists, it may be worth contacting Amazon Associate support for further assistance.

7. Account status: While your account is active and earning, there might be some restrictions or issues specific to your account that are causing these errors. Verifying your account status directly with Amazon could help rule this out.

To verify if your account is still authorized for PA-API access programmatically, you could set up a simple test request that you run periodically. If it consistently fails, it might indicate an issue with your account's API access.

Unfortunately, without seeing your exact request payload and headers, it's difficult to provide a known-good example. However, ensuring that your requests include all required parameters (like Operation, Service, Version, etc.) and are correctly signed is crucial.

If the issue persists after trying these suggestions, reaching out to Amazon's developer support for the PA-API would be advisable, as they can provide more specific guidance based on your account and usage patterns.  
**Sources**  
[Problem with Amazon API | AWS re:Post](https://repost.aws/questions/QUz3WKBBheRMq_AV8LOYCKfQ/problem-with-amazon-api)

PA-API v5 Requests Return 404 InternalFailure — Valid Associate Tag and Credentials

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