Can't delete IPAM pool (says there is an allocation to VPC)

Question

TL;DR: IPAM pool allocations shows allocation to a VPC, so I can't delete the IPAM pool. But VPC has no CIDR. Am I stuck in a deadlock?

I'm playing with IPAM and created a parent IPAM pool `ipam-pool-1`, then a child IPAM pool `ipam-pool-2`.
I associated this child IPAM pool `ipam-pool-2` to an existing VPC `vpc-1` to see how it works.
Now I wan't to delete all my IPAM pools (to start afresh with other netmask length) but to do this I need to delete CIDR of each one.

When I try to delete CIDR from `ipam-pool-2` I get:

> Failed deprovision (The CIDR has one or more allocations.)

Indeed the "Allocations" (of IPAM pool) tab shows an allocation to VPC `vpc-1`.

But this tab don't offer way to delete such allocation.

And the VPC has no CIDR, AWS CLI confirms this: the all returned associations are in "disassociated" state.

```
$ aws ec2 describe-vpcs
{
    "Vpcs": [
        {
            "VpcId": "vpc-1",
            "Ipv6CidrBlockAssociationSet": [
                {
                    "AssociationId": "vpc-cidr-assoc-0830cf26e3e292af8",
                    "Ipv6CidrBlock": "2a05:d012:474:2700::/56",
                    "Ipv6CidrBlockState": {
                        "State": "disassociated"
                    },
                    "NetworkBorderGroup": "eu-west-3",
                    "Ipv6Pool": "Amazon",
                    "Ipv6AddressAttribute": "public",
                    "IpSource": "amazon"
                },
                {
                    "AssociationId": "vpc-cidr-assoc-0ff5848dddcabfba3",
                    "Ipv6CidrBlock": "2a05:d022:f::/56",
                    "Ipv6CidrBlockState": {
                        "State": "disassociated"
                    },
                    "NetworkBorderGroup": "eu-west-3",
                    "Ipv6Pool": "IPAM Managed",
                    "Ipv6AddressAttribute": "public",
                    "IpSource": "amazon"
                },
                {
                    "AssociationId": "vpc-cidr-assoc-0461c03f7676c080a",
                    "Ipv6CidrBlock": "2a05:d012:d8f:8a00::/56",
                    "Ipv6CidrBlockState": {
                        "State": "disassociated"
                    },
                    "NetworkBorderGroup": "eu-west-3",
                    "Ipv6Pool": "Amazon",
                    "Ipv6AddressAttribute": "public",
                    "IpSource": "amazon"
                }
            ]
        }
    ]
```

If I try to use AWS CLI to release the IPAM pool allocation I get an error:

```
$ aws ec2 get-ipam-pool-allocations --ipam-pool-id ipam-pool-2
{
    "IpamPoolAllocations": [
        {
            "Cidr": "2a05:d022:f::/56",
            "IpamPoolAllocationId": "ipam-pool-alloc-034811",
            "ResourceId": "vpc-1",
            "ResourceType": "vpc",
            "ResourceRegion": "eu-west-3",
            "ResourceOwner": "8…"
        }
    ]
}

$ aws ec2 release-ipam-pool-allocation --ipam-pool-id ipam-pool-2  --cidr "2a05:d022:f::/56" --ipam-pool-allocation-id "ipam-pool-alloc-034811"
An error occurred (InvalidParameterValue) when calling the ReleaseIpamPoolAllocation operation: The allocation ID ipam-pool-alloc-1 is not valid. Cannot release allocation for resource type VPC.
```

What am I missing?

CDuv · Answer

It seems you just have to wait (24h?).

CIDR I could not de-provision **yesterday** because of existing allocation with a VPC are **now** allocation-free and thus de-provision-able.

Malini Agrawal · Answer

hi,
have you deleted the VPC?

wait few minutes to see the IPAM Auto-release the allocation ( IPAM should automatically release onces the VPC deleted.

doc:
https://docs.aws.amazon.com/vpc/latest/ipam/release-alloc-ipam.html#auto-release

i thought i copy past this doc in my previous answer, i should have asked you this before.

Best

Malini Agrawal · Answer

ok! got it.

you have already looked into it, but just in case:

To find commands references help for IPAM:

[https://docs.aws.amazon.com/cli/latest/reference/ec2/]()

Look under these sections:

get-ipam-pool-allocations

deprovision-ipam-pool-cidr

delete-ipam-pool

release-ipam-pool-allocation

Use Find Ctrl+F on page to quick search.

re:Post Agent · Answer

When you're trying to delete an IPAM pool but encountering issues due to allocations, you're facing a common challenge with IPAM resource management. Here's how to resolve this situation:

The error you're seeing occurs because you cannot delete an IPAM pool if there are allocations in it or CIDRs provisioned to it, even if the VPC shows the CIDR associations as "disassociated".

To resolve this issue, you have two options:

1. Release the allocation first, then delete the pool:
- Use the `release-ipam-pool-allocation` command to release the allocation from your VPC
- You'll need the IPAM pool ID and the allocation ID, which you can get with `describe-ipam-pools` and `get-ipam-pool-allocations` commands
- After releasing the allocation, you can deprovision the CIDR and then delete the pool

2. Use the cascade option to delete everything at once:
- When deleting the IPAM pool, you can use the `--cascade` option with the `delete-ipam-pool` command
- This will automatically release any allocations in the pool before deleting it
- This is useful when you don't want to remove allocations one by one

Note that when you release a CIDR that's managed by IPAM, it takes time for the CIDR to become available for future allocations - a few minutes in the Advanced Tier or up to 48 hours in the Free Tier.

For manual allocations specifically, you must either ignore/delete the resource CIDR (for private scope) or delete the resource CIDR (for public scope) before the allocation can be fully released.

Make sure to run these commands in the region that matches the locale of your IPAM pool.  
**Sources**  
[DeleteIpamPool - Amazon Elastic Compute Cloud](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DeleteIpamPool.html)  
[delete-ipam-pool — AWS CLI 2.27.41 Command Reference](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/delete-ipam-pool.html)  
[Release an allocation - Amazon Virtual Private Cloud](https://docs.aws.amazon.com/vpc/latest/ipam/release-alloc-ipam.html)  
[release-ipam-pool-allocation — AWS CLI 2.27.41 Command Reference](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/release-ipam-pool-allocation.html)  
[Amazon EC2 examples using AWS CLI - AWS SDK Code Examples](https://docs.aws.amazon.com/code-library/latest/ug/cli_2_ec2_code_examples.html)

Malini Agrawal · Answer

Hi,

Just a quick note — IPAM pools work in both private and public scopes, but only pools in the private scope can be cascade deleted.

AWS doc:-

```
https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ec2/client/delete_ipam_pool.html
```

Boto3 doc delete_ipam_pool:

`https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ec2/client/delete_ipam_pool.html`

Best

Can't delete IPAM pool (says there is an allocation to VPC)

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