AWS Config and S3 Delivery Channel issue

Today, I was fighting the enablement of a delivery channel for AWS Config, and every time I received an error:

InsufficientDeliveryPolicyException: Insufficient delivery policy to s3 bucket

It took half a day to figure out a small but essential nuance — it turns out that AWS Config does not support the delivery channel to an Amazon S3 bucket where object lock is enabled with default retention enabled.

So, if you face the same issue, check if your bucket's object lock is disabled.