Error: dynamodb value cannot be null. (parameter 'type')

“Value cannot be null. (Parameter ‘type’)” is a client-runtime exception, commonly seen in .NET reflection or mapping code. It is not proof that DynamoDB rejected a NULL attribute. The stack trace must identify which library received a missing type.

1. Capture the full exception and inner exception, then locate the first application or SDK mapping frame.
2. Check the model type passed to the persistence API, any runtime type lookup, and custom converters. A failed type lookup can return null before a DynamoDB request is sent.
3. Verify the model’s key mapping and the SDK packages used by the deployed application. Compare a minimal low-level request with the object-mapping path to isolate the failing layer.
4. If only a trimmed or AOT build fails, investigate preserved model metadata using the SDK’s supported deployment guidance. Do not assume that diagnosis without reproducing it.

DynamoDB supports NULL for non-key attributes. Removing every null field is not a verified fix for a missing runtime type. Without the exact stack trace and SDK version, this wording does not establish one specific defect or workaround.

See DynamoDB types and ArgumentNullException reference.