Guidance request: what specifically happens to running clusters older than 3.13.0 when python 3.9 lambda is blocked on june 1st

[chrisdag]

Hello!

I am trying to understand what happens from a behavior and operations view to existing ParallelCluster environments that don't upgrade to 3.14.0 before June 1st 2026

From what I can see:

• lambda python 3.9 went out of support in late 2025
• AWS is blocking new lamdas that use v 3.9 on June 1st 2026
• AWS is blocking existing layer updates that use v3.9 on July 1st 2026

I'd like to understand and communicate to people needing to plan their upgrades.

My guess as to what will happen is this, looking for a sanity check:

Existing ParallelCluster environments older than v3.14.0 running after June 1st 2026

• Existing clusters will continue to operate just fine, including auto-scaling compute fleets (no lambda create/updates in this scenario)
• Existing clusters can upgrade compute fleet configuration details (no lambda involved; just new launch templates and auto-scaling configs)
• No new clusters can be deployed (because this does create v3.9 lambda functions)
• (??) Cluster updates requiring loginNode or headNode replacement will fail (Not sure; are lambdas updated in this scenario?)

Thanks!

[gmarciani]

Hi @chrisdag ,

your analysis is correct. Existing clusters are not impacted.
When Lambda will block Py39 runtime, it will not be possible to create new cluster or new custom AMI with pcluster < 3.14.0.
Our recommendation is to upgrade to pcluster 3.14.0+ (3.14.2 at the time of writing).

For ParallelCluster UI (PCUI) users, the impact will be that it will not be possible to deploy a PCUI < 2025.04.0.
Our recommendation is to upgrade to PCUI 2025.04.0.

(??) Cluster updates requiring loginNode or headNode replacement will fail (Not sure; are lambdas updated in this scenario?)

No impact in this scenario.

Thanks

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