Amazon S3 Error: AccessControlListNotSupported 🚫

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Access Control List. An older S3 permission mechanism that can grant access to individual objects and buckets.

 

Amazon S3 Error: AccessControlListNotSupported 🚫

You may encounter an error similar to: 

An error occurred (AccessControlListNotSupported) when calling the PutObject operation:
The bucket does not allow ACLs

At first glance, this looks like a permissions problem.

Usually it isn't.

In most cases, AWS is telling you that the bucket has been configured to disable ACLs entirely.

📌 Key Term

ACL

Access Control List. An older S3 permission mechanism that can grant access to individual objects and buckets.

What AWS Is Telling You

Modern S3 buckets often use:

  • IAM Policies
  • Bucket Policies
  • Object Ownership

instead of ACLs.

When a bucket has ACLs disabled, S3 rejects requests that attempt to set them.

AWS is essentially saying:

"This bucket no longer uses ACLs."

Why This Happens

Many older applications automatically include ACL settings during uploads.

For example: 

aws s3 cp file.txt s3://my-bucket/ --acl public-read

Years ago this was common.

Today many organizations disable ACLs completely.

When that happens, the upload fails.

📌 Common Mistake

Adding:

--acl public-read

when the bucket is configured with ACLs disabled.

Check Object Ownership

Open the S3 console and review: 

Bucket
↓
Permissions
↓
Object Ownership

If you see: 

Bucket owner enforced

ACLs are disabled.

This is now AWS's recommended configuration.

📌 Key Term

Bucket owner enforced

An Object Ownership setting that disables ACLs and makes policy-based permissions the source of truth.

The Fastest Fix

Remove ACL-related parameters from your upload process.

Instead of: 

aws s3 cp file.txt s3://my-bucket/ --acl public-read

Use: 

aws s3 cp file.txt s3://my-bucket/

Then manage access through:

  • IAM Policies
  • Bucket Policies

instead of ACLs.

Check Your SDK or Application

Many applications quietly set ACLs behind the scenes.

Examples include:

  • Older deployment tools
  • Legacy scripts
  • Third-party backup software
  • Older SDK examples

If the error persists, inspect the application configuration for ACL settings.

📌 Remember

This error is usually not about missing permissions.

It's about using a permission mechanism that the bucket no longer supports.

The Big Idea

AWS has been moving customers away from ACLs and toward policy-based access control.

When you see AccessControlListNotSupported, the bucket is often working exactly as designed.

The solution is usually simple:

  1. Remove ACL settings
  2. Use bucket policies or IAM policies
  3. Confirm Object Ownership is set to Bucket owner enforced

Once you make that change, uploads typically succeed without further modification.

Happy troubleshooting! ☁️

Aaron Rose is a software engineer and technology writer at tech-reader.blog.

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