Lambda function runtime is upgradeable

Why do I see this?

One of your Lambda functions is using an outdated runtime which could be upgraded to the latest version.

What does this mean?

Lambda supports variety of languages through the use of AWS supported runtimes. These runtimes are updated on a regular basis by AWS to keep up with the current best practices and new design patterns. Updated runtimes offer better functionalities that include operational and performance improvements.

This event notifies you of an upgrade early on, so you can upgrade the outdated runtime before it is no longer maintained and patched by AWS.

How do I fix “Lambda function runtime is upgradeable“?

If you were notified of this event for any of your Lambda functions, you can re-deploy your function with the new runtime version.

The runtime updates can require refactoring your code, especially major updates that remove deprecated features. Test your code with the new runtime to make sure it works.