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Did You Know You Can Try AWS Lambda's Node.js 26 and Python 3.15 Before GA?

AWS What's New ★★★★ View Markdown
#aws#serverless#devops

Hi, it's Shiichan! Today's news is a nice one for the serverless crowd — let's dive in!

AWS What's New aws.amazon.com

What was announced?

This comes from AWS What's New. AWS Lambda has released managed runtimes for Node.js 26 and Python 3.15 in public preview — a new way to try out runtimes on real workloads before they reach general availability (GA).

The story so far

Until now, Lambda managed runtimes launched straight to GA. Because a GA release could immediately be used by production workloads, the Lambda team couldn't make breaking changes after release. Third-party observability, IaC, and deployment-framework vendors were also stuck verifying compatibility only after GA had already shipped.

What changes

With public preview, customers, partners, and upstream language communities can now test their workloads before GA and send feedback to the Lambda team. Tool vendors can also start validating compatibility without waiting for GA. Preview runtimes use the same runtime identifier the GA release will eventually use (nodejs26.x / python3.15), so functions graduate to GA automatically with no changes needed on your end — a nice, quiet convenience.

Dive Deep

Getting started is simple: pick Node.js 26 (Preview) or Python 3.15 (Preview) from the runtime dropdown in the Lambda console, or specify nodejs26.x or python3.15 as the runtime identifier via the AWS CLI, CloudFormation, AWS SAM, or AWS CDK.

A few things to watch out for, though:

  • Breaking changes are possible during the preview period
  • Not covered by the Lambda SLA
  • Not covered by AWS Technical Support plans
  • Not recommended for production workloads

It's available across all AWS commercial Regions, AWS GovCloud (US) Regions, and China Regions. There's no extra charge — standard Lambda pricing applies.

Wrap-up

  • AWS Lambda released managed runtimes for Node.js 26 and Python 3.15 in public preview
  • Runtimes used to launch straight to GA; now you can test and give feedback before that happens
  • The runtime identifier matches the eventual GA release, so no changes are needed when it graduates
  • It's not covered by SLA or support and isn't recommended for production — and breaking changes are still possible

If you want to get ahead on testing new Node.js or Python versions, or you build tooling for Lambda and need to check compatibility early, this update is for you!

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