301 Moved Permanently — The Amazon S3 Region Redirect Trap

#aws#s3#devops#cloud

When the wrong endpoint makes your bucket vanish.

Problem

You’ve got a bucket you know exists — but every request to S3 throws back:

<Error>
  <Code>301 Moved Permanently</Code>
  <Message>Moved Permanently</Message>
  <Endpoint>my-bucket.s3.us-west-2.amazonaws.com</Endpoint>
</Error>

To your users, it looks like the bucket is gone. To your dashboard, it looks like downtime. But the truth? The bucket is alive and well — just in a different region.

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Clarifying the Issue

The 301 Moved Permanently error happens when:

• A bucket is created in one AWS region, but requests are made to the global s3.amazonaws.com endpoint or the wrong regional endpoint.
• DNS or SDK defaults route traffic to the wrong region.
• Applications assume buckets are globally addressable, when in fact they’re region-scoped.

S3 doesn’t auto-fix this for you. Instead, it redirects — but if your client doesn’t follow redirects correctly (or ignores the hint), you hit a wall. Some SDKs or older client libraries fail here: outdated versions may not implement redirect handling properly, or custom HTTP stacks may disable it by default.

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Why It Matters

• False outages: Buckets appear missing, halting pipelines.
• User disruption: Apps fail instead of gracefully retrying with the right endpoint.
• Security gaps: Misconfigured apps may retry endlessly, logging sensitive keys.
• Operational churn: Engineers waste time “hunting” for buckets that are healthy in another region.
• Hidden costs: Misrouted traffic may trigger cross-region data transfer charges, adding surprise costs to your bill.

This isn’t about S3 being unreliable. It’s about being precise with regional endpoints.

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Key Terms

• 301 Moved Permanently: HTTP response indicating the resource lives elsewhere.
• Regional Endpoint: The correct URL tied to the region where your bucket resides (e.g., s3.us-west-2.amazonaws.com).
• Global Endpoint: The older s3.amazonaws.com endpoint that often leads to region mismatches. It exists for legacy compatibility and is still supported, but using it can create confusion.
• Bucket Location: The actual AWS region a bucket belongs to.

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Steps at a Glance

1. Confirm the error and capture the endpoint hint.
2. Check the bucket’s actual region.
3. Update your client config to use the correct region.
4. Fix SDK and application defaults.
5. Document and enforce regional usage.

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Detailed Steps

1. Confirm the Error and Capture the Endpoint Hint
The 301 response often includes the “right” endpoint in the message. Save it.

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2. Check the Bucket’s Actual Region

aws s3api get-bucket-location --bucket my-bucket

Output shows the true region (e.g., us-west-2).

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3. Update Your Client Config

aws configure set region us-west-2

Or set it per call:

aws s3 ls s3://my-bucket --region us-west-2

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4. Fix SDK and Application Defaults

Example in Python boto3:

import boto3
s3 = boto3.client('s3', region_name='us-west-2')

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5. Document and Enforce Regional Usage

• Require devs to use regional endpoints.
• Bake region checks into CI/CD.
• Monitor for 301 errors in logs to catch misconfigurations early.

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Conclusion

The 301 Moved Permanently error isn’t an outage — it’s a map problem. Your bucket hasn’t disappeared; your request just went to the wrong neighborhood. Some SDKs can’t follow the detour, which makes precision even more important. By checking the bucket’s location, updating clients, and enforcing regional precision, you keep your S3 calls on target.

With S3, geography matters. Respect the regions, avoid legacy global endpoints, and the “mystery outages” vanish.

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Aaron Rose is a software engineer and technology writer at tech-reader.blog and the author of Think Like a Genius.