Impossible to delete VPC / Network Interface

Here are some of common cases:

• Active load balancer that was attached to the ENIs
• Active RDS instances
• DMS Replication Instance
• VPC links from API gateway
• VPC Endpoint services
• Unused NAT gateways
• Unused ECS/EKS clusters

You'd need to delete these resources first based on what's applicable in your case. Note that these are just few common services, where we see this attached but there can be others too.

See, where are your security groups being used, can you detach security groups from those resources first, then try deleting the security groups first, if you see issues removing security groups, remove inbound/outbound rules from the security groups, then try deleting the security groups and then ENIs

Additional command references:

1. aws ec2 delete-network-interface --network-interface-id <eni-name>

2. aws ec2 describe-network-interfaces --filters 'Name=vpc-id,Values='$vpc | grep NetworkInterfaceId

Also, if you have support plan, I'd suggest you to reach out to AWS Support by logging a case under Technical category. They are well equipped to address the issue in a precise way if none of the above helps.

Hope you find this helpful.

Comment here if you have additional questions, happy to help.

Abhishek