Error: dynamodb cannot read property '0' of undefined

Cannot read property '0' of undefined means code indexed a value that was not defined. A missing Items array or a mismatched SDK command can cause it; importing ScanCommand differently is not a universal fix.

import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, ScanCommand } from "@aws-sdk/lib-dynamodb";

const db = DynamoDBDocumentClient.from(new DynamoDBClient({}));

const response = await db.send(new ScanCommand({ TableName: "People" }));
const first = response.Items?.[0];
console.log(first?.pk);

This example imports ScanCommand from @aws-sdk/lib-dynamodb and uses DynamoDBDocumentClient, so values are native JavaScript types. For low-level DynamoDBClient, use commands from client-dynamodb and typed AttributeValue inputs and outputs.

Inspect the stack trace. If it points into your own code, check the field before indexing and distinguish GetItem's Item from Query or Scan's Items. If it points into serialization, inspect command imports and request types. An empty first page may still have LastEvaluatedKey, so paginate before deciding no matching items exist.

See v3 client examples and AWS documentation.