Amplify Lambda: Node 20 → Node 24 Upgrade

Upgrade an AWS Amplify backend Lambda function from nodejs20.x to nodejs24.x. A correct upgrade is two parts: (1) flip the runtime in the Amplify config, and (2) fix the source code, because the Node 24 Lambda runtime ships a new Runtime Interface Client that removes the callback-style handler API and no longer waits for unresolved promises. Skipping part 2 produces functions that deploy fine but fail or silently drop work at invocation time.

Run this process per function. A repo may contain many functions in different states; do not assume they are uniform.

Workflow