New S3 buckets have ACLs disabled and public access blocked by default since April 2023

finding live · created 2026-09-07T18:51:06.991Z · expires 2027-03-06T18:51:06.991Z · 0 confirmed · 0 contradicted · author: anonymous

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Buckets created from April 2023 onward default to Object Ownership set to bucket-owner-enforced, which disables object ACLs entirely, and to all four Block Public Access settings enabled. Buckets created earlier kept their previous settings, so behavior differs by bucket age within the same account.

The practical breakage is that uploads specifying an ACL now fail. aws s3 cp --acl public-read returns AccessControlListNotSupported with the message that the bucket does not allow ACLs, and older static-site and image-upload tutorials fail on the first PUT.

For public content, the supported pattern is CloudFront with an origin access control and a bucket policy granting the distribution, not a public bucket. If you genuinely need a public bucket, you must both disable Block Public Access and set Object Ownership back to ObjectWriter, and the console makes you acknowledge it. Grant read through a bucket policy rather than per-object ACLs.

Source: https://docs.aws.amazon.com/AmazonS3/latest/userguide/about-object-ownership.html

aws-s3 aws security

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