InvalidCypherTextException when reading an encrypted DynamoDB table which has been restored from a backup
If you attempt to read encrypted data from a DynamoDB table which has been restored from a backup to a DynamoDB table which doesn’t match the original table name, you may see the following errors:
InvalidCiphertextException: An error occurred (InvalidCiphertextException) when calling the Decrypt operation
UnwrappingError: Failed to unwrap AWS KMS protected materials
TL;DR the restored DynamoDB table must have the same name as the original DynamoDB table, and be restored to the same account that it was originally created in.