Announcement: Updated default retry behavior (2026)

[millems]

This issue tracks the 2026 retry updates for AWS SDK for Swift. See the announcement blog post for the full story across all AWS SDKs, including how to tell if you are affected.

Status

Opt-in	Coming in the following weeks. We will update this issue when the release ships.
Opt-in flag	AWS_NEW_RETRIES_2026=true
Default rollout	No sooner than November 2026

What changed

When you set AWS_NEW_RETRIES_2026=true, the default values for standard mode are updated per the table below. The retry mode itself does not change.

If you have explicitly configured max attempts or backoff, your value takes precedence for that setting.

Setting	Before	After
Transient (non-throttling) base delay	1,000 ms	50 ms
Throttling base delay	1,000 ms	1,000 ms (unchanged)
Max attempts	3	3 (unchanged)
Transient retry quota cost	5 tokens	14 tokens
DynamoDB and DynamoDB Streams
Transient (non-throttling) base delay	1,000 ms	25 ms
Throttling base delay	1,000 ms	1,000 ms (unchanged)
Max attempts	3	4

DynamoDB defaults use a shorter base delay to match its low-latency profile. The additional attempt keeps the last retry's maximum backoff comparable to the general default.

Transient errors (such as 500s and connection resets) now use a much shorter backoff than throttling errors (where the service asks you to slow down). For details on backoff timing, error classification, and the retry quota, see Retry behavior in the AWS SDKs. For retry mode selection and configuration options, see Retry behavior in the AWS SDKs.

How to opt in

Once the release ships (we will update this issue), set the environment variable:

export AWS_NEW_RETRIES_2026=true

How to revert

During the opt-in period, remove the environment variable:

unset AWS_NEW_RETRIES_2026

After the default rollout (no sooner than November 2026), the AWS_NEW_RETRIES_2026 flag will be removed. The updated behavior cannot be reverted because this SDK does not support legacy retry mode. You can still override max_attempts.

If this is a concern for your use case, please let us know in this issue.

Where you might notice a difference

For most workloads, the change is invisible or strictly better. Transient errors recover faster because the base delay is significantly shorter.

• Retry quota activates sooner for transient errors. Each transient retry costs 14 tokens (previously 5 for most errors). During sustained transient failures (such as 500s and connection resets), the retry quota triggers at a lower failure rate than the previous version of standard mode. Throttling retries cost 5 tokens.
• Long-polling operations now back off when the retry quota is depleted. Operations like SQS.ReceiveMessage apply a backoff delay before returning an error, even when retries are blocked. Without this, polling loops tighten during outages, spiking client CPU usage and generating additional load that can delay recovery. For details, see long-polling operations.

Overriding specific settings

You do not have to accept all changes as a bundle. If you opt in but want to keep a specific previous value, set it explicitly. Precedence applies per setting.

For example, to use the new backoff timing but keep a higher DynamoDB max attempts:

import AWSDynamoDB

var config = try await DynamoDBClient.DynamoDBClientConfig()
config.maxAttempts = 9

let client = DynamoDBClient(config: config)

For the full list of configurable settings and their precedence, see Retry behavior in the AWS SDKs.

Feedback

If you encounter unexpected behavior or have questions, comment on this issue. Your feedback during the opt-in period directly shapes when and how we make this the default.

[dayaffe]

Use with opt-in flag AWS_NEW_RETRIES_2026=true is now available from version 1.7.9!