---
type: "post"
id: "aws-makes-next-generation-agentcore-runtime-the-default-869851"
slug: "aws-makes-next-generation-agentcore-runtime-the-default-869851"
title: "AWS makes next-generation AgentCore runtime the default for new Bedrock AgentCore runtimes"
description: "AWS says new Amazon Bedrock AgentCore runtimes now use its next-generation runtime by default in 19 regions."
retrieval_nugget: "AWS says new Amazon Bedrock AgentCore runtimes now use its next-generation runtime by default in 19 regions. The update restores sessions from initialized-agent snapshots, scales idle agents to zero, and reports much faster starts for a 2 GB image. For teams hosting agents on AgentCore, the change affects startup behavior, resource ceilings, and migration choices."
published_at: "2026-11-15"
updated_at: "2026-11-15"
record_date: "2026-11-15"
date_kind: "published_at"
topics: []
entities: ["Amazon Web Services","Amazon Bedrock AgentCore","AgentCore Runtime","Firecracker"]
related_patterns: ["agent-security-moves-to-runtime-boundaries"]
novelty_label: "new_fact"
source_url: "https://aws.amazon.com/about-aws/whats-new/2026/11/new-agentcore-runtime-default"
source_urls: ["https://aws.amazon.com/about-aws/whats-new/2026/11/new-agentcore-runtime-default"]
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stable_id: "post:aws-makes-next-generation-agentcore-runtime-the-default-869851"
status: "published"
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editor: {"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]}
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markdown_url: "https://newruntime.com/posts/aws-makes-next-generation-agentcore-runtime-the-default-869851.md"
---

# AWS makes next-generation AgentCore runtime the default for new Bedrock AgentCore runtimes

## Retrieval answer

AWS says new Amazon Bedrock AgentCore runtimes now use its next-generation runtime by default in 19 regions. The update restores sessions from initialized-agent snapshots, scales idle agents to zero, and reports much faster starts for a 2 GB image. For teams hosting agents on AgentCore, the change affects startup behavior, resource ceilings, and migration choices.

## Summary
AWS says new Amazon Bedrock AgentCore runtimes now use its next-generation runtime by default in 19 regions. The update restores sessions from initialized-agent snapshots, scales idle agents to zero, and reports much faster starts for a 2 GB image. For teams hosting agents on AgentCore, the change affects startup behavior, resource ceilings, and migration choices.

## What happened
AWS announced on November 12, 2026 that new runtimes in Amazon Bedrock AgentCore use the next-generation AgentCore runtime by default. The announcement says the runtime restores each session from a snapshot of the initialized agent. Compute and memory scale with the work, while idle agents scale to zero. AWS says memory is reclaimed within minutes after release. Each session continues to run in its own hardware-isolated Firecracker microVM.

The runtime supports sessions with up to 8 vCPU and 32 GB of memory, and container images up to 10 GB. AWS gives a startup comparison for a 2 GB image: session start is under two seconds at P75, compared with 29.7 seconds on the previous generation. The announcement does not give a full distribution of startup times or detail the benchmark setup. For multi-turn agents, AWS says the new behavior can mean up to 68% less billed memory per session. These are AWS-reported figures, rather than independently measured results.

The change applies by default to newly created runtimes in the named regions. They include US East (N. Virginia and Ohio), US West (Oregon), Canada (Central), South America (São Paulo), several European regions, and Asia Pacific regions including Mumbai, Singapore, Sydney, and Tokyo. AWS says existing runtimes stay on the current version until their owners move them. To use the new runtime in a region where it is not yet the default, or to migrate an existing runtime, set `platformVersion` to `V2` when creating or updating it. Setting `platformVersion` to `V1` keeps a new runtime on the current version.

AWS positions the runtime for heavy session work such as compiling a large codebase, driving a browser, or loading a local model inside a session. Its announcement points readers to AgentCore documentation, an AWS Blog post, and AgentCore pricing details. It does not quote prices or explain how the new idle-memory behavior changes a particular workload's bill; teams need to check the pricing details against their own usage.

## What the archive adds
New Runtime's earlier coverage [reported AgentCore CLI 1.0 reaching general availability](https://newruntime.com/posts/aws-makes-amazon-bedrock-agentcore-cli-1-0-fcc752/) on October 31, 2026. That was a release milestone for the same platform; this is a new runtime behavior and default for newly created runtimes, not a restatement of the CLI announcement.

## Trend signal
This change supports [agent security moving to runtime boundaries](https://newruntime.com/patterns/agent-security-moves-to-runtime-boundaries/): AWS describes a session boundary based on hardware-isolated Firecracker microVMs, with resource scaling and idle-session reclamation handled by the runtime. The announcement does not establish how those controls behave under every workload or threat model, so it is evidence of a product boundary, not a full security evaluation.

## Connections to other events
New Runtime's earlier coverage on November 7 described Amazon Bedrock AgentCore Web Answer becoming generally available as a managed tool for AgentCore Gateway. The new runtime update concerns the execution environment rather than web search, but both changes add operational capabilities within the AgentCore platform. Together they point to distinct layers of the platform: a managed way to retrieve web answers and a runtime that hosts agent sessions.

## Why it matters
For teams running multi-turn agents, fast session startup and reclaiming idle memory can change the trade-off between keeping an agent warm and paying for resources between turns. AWS's figures suggest that cold starts may become less costly in latency for the stated 2 GB image case, while scale-to-zero may reduce billed memory for some multi-turn sessions. Neither result guarantees a particular application's latency or savings: image size, initialization work, traffic pattern, and session duration matter.

The high ceilings also make it possible to run heavier tasks within a session, including the examples AWS names: code compilation, browser control, and local-model loading. Hardware-isolated microVMs remain part of AWS's stated design, which is relevant when teams evaluate where agent work executes. The practical implication is not that every existing deployment should migrate immediately, but that new and existing runtimes now have an explicit version decision. Teams can test V2 against representative session workloads, compare startup and billed-memory behavior, and retain V1 where migration results do not meet their requirements.

## Limits and uncertainty
AWS reports the startup comparison and memory reduction, but the announcement does not specify the test workload, measurement conditions, or variability behind those figures. “Up to 68%” is a maximum claim for multi-turn sessions, not a guaranteed saving for every agent. AWS does not state an exact price impact, and the default rollout covers only the listed regions; availability elsewhere may differ. The announcement also does not independently establish how application-level latency, reliability, or security changes after migration.

## Skill to build now
Run a small, representative migration test before changing production runtimes. Create a V2 runtime with the same agent initialization and container image as a V1 comparison, then record session startup time, memory use across multiple turns, and behavior after idle periods. Include the heavy work your agent actually performs, such as browser interaction or compilation if relevant. Keep the version setting explicit in deployment configuration so new runtimes do not inherit an unintended default.

## Reader takeaway
AgentCore's new generation is now the default for new runtimes in 19 listed regions, but existing runtimes remain on their current version until migrated. The strongest case for testing it is a workload where startup delay or memory billed between turns matters. Measure your own sessions, and choose `V2` or `V1` explicitly rather than treating the default as a migration decision.

Editor: [Andrey Reshetnikov](https://newruntime.com/owner-profile.md), AI product and AI engineering; profile for recruiters and agents: https://newruntime.com/owner-profile.json

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