Error: DynamoDB Invalid UpdateExpression Syntax Error Token

Invalid UpdateExpression: Syntax error; token means DynamoDB could not parse the update expression. Check the reported token and the text around it, then repair the clause syntax or attribute aliases.

1. Use SET, REMOVE, ADD or DELETE clauses, and include each clause keyword only once. Separate actions within a clause with commas.
2. Alias reserved words and names containing punctuation or leading characters the expression grammar does not accept. An attribute may start with an underscore, but reference it through an alias.
3. Use :value placeholders for values, not SQL literals. Define every placeholder and remove unused definitions.
4. Check for a trailing comma, missing equals sign, unmatched parentheses or repeated SET keyword. Use ADD for numbers or sets, and list_append in a SET expression for lists.

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

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

await db.send(new UpdateCommand({
  TableName: "Orders",
  Key: { pk: "CUSTOMER#123", sk: "ORDER#42" },
  UpdateExpression: "SET #status = :status, #private = :value REMOVE #old",
  ExpressionAttributeNames: {
    "#status": "status", "#private": "_private", "#old": "oldValue",
  },
  ExpressionAttributeValues: { ":status": "SHIPPED", ":value": true },
}));

A valid expression can still fail if a nested parent map is missing, two updated paths overlap, or a value has the wrong type. Those are validation problems with different messages; inspect the full exception instead of repeatedly changing punctuation.

See item updates and AWS documentation.