Error: DynamoDB Error 413

HTTP 413 means a request payload was too large for the component that rejected it. Check whether the response came from DynamoDB, an API gateway, a reverse proxy or another service before changing the data model.

1. Inspect the response body, headers, endpoint and request ID. The HTTP status alone does not identify which limit was exceeded.
2. Check each DynamoDB item's size, including attribute names and values. The item limit is 400 KB; an oversized item normally causes a validation error rather than proving that DynamoDB emitted the 413.
3. For BatchWriteItem, check the 16 MB request limit and 25-operation limit as well as each item's size. The JSON wire representation can be larger than stored item size.
4. If a proxy rejects the body, use its documented limit and adjust the request or architecture there.

Move large blobs to object storage and keep a reference in DynamoDB, or split data into smaller items with a deliberate access pattern. Splitting a batch fixes aggregate request size, but not an individual oversized item. Check update results too: the final item must fit the item-size limit.

See item size calculator and AWS documentation.

BatchWriteItem request limits distinguish stored item size from request size.