Error: ExpressionAttributeValues contains invalid value: One or more parameter values were invalid: An AttributeValue may not contain an empty string

This error means that you’ve used query which some empty value and DynamoDB does not accept that. There are two possible ways of fixing:

1. Find and fix empty value, replace with something meaningful or remove from query at all
2. In DocumentClient constructor add convertEmptyValues param set to true:

const DynamoDB = new AWS.DynamoDB.DocumentClient({
    convertEmptyValues: true
});

This will make DynamoDB SDK to automatically convert all empty values to null.