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@aws-sdk/client-s3

What changed in @aws-sdk/client-s3 3, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-19.

2 security17 new APIs and options4 behavior and defaults4 fixes and other

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@aws-sdk/client-s3 327 changes

Security 2

  • Adds support for blocking SSE-C writes to general purpose buckets.

    3.935.0release notes

  • CopyObject supports conditional writes on the destination key to prevent unintended object modifications.

    3.919.0release notes

New APIs and options 17

  • Adds an optional S3 Inventory field reporting the reference date used to evaluate an object's Intelligent-Tiering tier-transition eligibility; it is populated for Intelligent-Tiering objects and blank for others.

    3.1144.0release notes

  • S3 Object Lock APIs that support Object Lock parameters now accept DefaultEventHoldDuration at the bucket level.

    3.1128.0release notes

  • S3 Object Lock APIs that support Object Lock parameters now accept EventHold at the object level.

    3.1128.0release notes

  • S3 Object Lock APIs that support Object Lock parameters now accept EventHoldDuration at the object level.

    3.1128.0release notes

  • AWS Backup lets you create read-only access points for Amazon S3 recovery points, so you can access backup data using S3 APIs without initiating a restore.

    3.1105.0release notes

  • S3 Metadata now supports configuring an annotation table.

    3.1070.0release notes

  • New APIs let developers create, retrieve, list, and delete annotations attached directly to objects, with up to 1000 annotations of up to 1 MB each.

    3.1070.0release notes

  • Adds MD5, SHA-512, XXHash3, XXHash64, and XXHash128 as checksum algorithms for S3 data integrity.

    3.1035.0release notes

  • Adds support for S3 Inventory on directory buckets (S3 Express One Zone).

    3.1035.0release notes

  • Bucket Metrics configuration is now supported for directory buckets.

    3.1021.0release notes

  • Adds support for account regional namespaces, a reserved subdivision of the global bucket namespace where only your account can create general purpose buckets.

    3.1008.0release notes

  • Adds support for changing the server-side encryption type of objects in general purpose buckets.

    3.978.0release notes

  • Clients can select a protocol by class constructor.

    3.953.0release notes

  • Adds the optional LifecycleExpirationDate field to S3 Inventory configurations.

    3.952.0release notes

  • Adds FSX_ONTAP as an S3 storage class.

    3.943.0release notes

  • Adds support for enabling or disabling ABAC on a general purpose bucket.

    3.937.0release notes

  • S3 Express now supports IPv6 dual-stack.

    3.925.0release notes

Behavior and default changes 4

  • The client validates outpost access point resource names.

    3.1044.0release notes

  • The valid AWS Region values for the LocationConstraint parameter for general purpose buckets were updated.

    3.1026.0release notes

  • Additional validation is applied to Outpost bucket names.

    3.958.0release notes

  • AWS REST XML clients now use schema-serde for serialization.

    3.931.0release notes

Fixes and other changes 4

  • XML entities are parsed using XML 1.1 behavior.

    3.1038.0release notes

  • Errors with a 200 status code are now retried.

    3.1035.0release notes

  • The adaptive retry throttling detection fix is synced.

    3.1021.0release notes

  • Service exceptions are decorated with unmodeled fields, making those fields available to developers.

    3.932.0release notes