Reading Lambda runtime deprecation notices
A mail like “[Action Required] AWS Lambda end of support for Node.js 20” is telling you that a runtime you are using is losing support. Nothing stops the next morning, but leave it long enough and the functions can no longer be updated and no longer get security fixes. You need the deadline and the affected functions in hand, and a plan per customer.
Last updated: 2026-09-22
What a runtime deprecation notice means
Lambda runtimes are retired in stages, following the end of support set by each language's own community. Past the end-of-support date, functions that already exist keep running, but they fall outside AWS's security patches and technical support. After that, creating new functions on that runtime is blocked, and later still, so is updating the ones that exist.
So putting it off because “nothing is going to stop” surfaces the problem in the worst possible order: on the day something has to be fixed and the code can no longer be updated. The notice carries the end-of-support date and the functions in the account that are affected.
What these mails make easy to miss
This mail goes to every account that has a function on the affected runtime. Hold ten customer accounts and ten mails with the same subject line land together. Which function sits in which account is only in the body, so going by the subject, treating them all as “the same notice” and marking the lot read is exactly how one gets left undone.
The notice does not come just once, either: as the deadline gets closer it is sent again. Plan the response off the first one and write it into the ledger, and the repeats can be waved through, because the work is already under way.
What Sabaki does with them
Sabaki works out the customer from the account ID in the body and, identical subject lines and all, files the mails per customer in the inbox. The summary names the runtime, when its support ends and which functions the body lists, and that end-of-support date is shown as the deadline. How far the response has got is tracked per customer in the response ledger, so “Company B is done, Company C is not” is there the moment you open the inbox.
Example: the mail that arrives, and what Sabaki shows
The subject and body imitate a real notification. Account IDs and dates are fictional.
- From
- Amazon Web Services <no-reply-aws@amazon.com>
- Subject
- [Action Required] AWS Lambda end of support for Node.js 20 [AWS Account: 987654321098]
Hello,
We are contacting you as we have identified that your AWS Account currently has one or more Lambda functions using the Node.js 20 runtime.
We are ending support for Node.js 20 in AWS Lambda on November 30, 2026. After this date, Lambda will no longer apply security patches or other updates to the runtime. Function creation using this runtime will be blocked at a later date, followed by function updates.
The following functions in the ap-northeast-1 region are affected: report-batch, image-resize.
The Node.js 20 runtime behind the Lambda functions in Company B's production account loses support on 30 November 2026. Two functions are affected: report-batch and image-resize.
Past that date the functions keep running, but they fall outside security fixes, and after that creation is blocked and, later, updates too. Move both functions to a newer Node.js runtime before the date, and check they still work. A migration usually drags a dependency update along with it, so the safe move is to agree the work window with the customer early.
If a mail with the same subject arrives from Company A's account too, it lands as a separate notification in Company A's inbox, with Company A's function names in its summary.
Working the response through
A runtime migration runs into the customer's budget and calendar, so having what you need to quote it ready as soon as the notice arrives is what lets you move fast.
- Write the function names and the deadline from the explanation into that customer's response ledger, and record that the work is under way
- Use the summary as it stands for the message to the customer, and propose a schedule and a cost for the migration work
- Mark it “Handled” once the work is done, and archive the repeat notices together by searching for the subject
Forward one AWS notification and it comes back explained
The Free plan covers one account and one seat, with no credit card. Nothing changes on the AWS side, and no access keys are registered.
Related questions
Related guides
If this helps, pass it on to someone who needs it.