kubernetes/kops · error

expecting exactly 1 address prefix for %q, found %d: %+v

Error message

expecting exactly 1 address prefix for %q, found %d: %+v

What it means

Validation guard in the Azure VNet Find: kOps models a VNet with exactly one address prefix, and the discovered network has a different count (zero or multiple prefixes). Fires when adopting a pre-existing VNet whose CIDR layout does not match kOps' single-CIDR assumption.

Source

Thrown at upup/pkg/fi/cloudup/azuretasks/virtualnetwork.go:87

	}

	if found.ID == nil {
		return nil, fmt.Errorf("found virtual network without ID")
	}
	if found.Properties == nil {
		return nil, fmt.Errorf("found virtual network without properties")
	}
	if found.Properties.ProvisioningState != nil && *found.Properties.ProvisioningState == network.ProvisioningStateFailed {
		klog.Warningf("found virtual network %q in failed provisioning state", *n.Name)
		return nil, nil
	}
	if found.Properties.AddressSpace == nil {
		return nil, fmt.Errorf("found virtual network without address space")
	}

	addrPrefixes := found.Properties.AddressSpace.AddressPrefixes
	if len(addrPrefixes) != 1 {
		return nil, fmt.Errorf("expecting exactly 1 address prefix for %q, found %d: %+v", *n.Name, len(addrPrefixes), addrPrefixes)
	}
	return &VirtualNetwork{
		Name:      n.Name,
		Lifecycle: n.Lifecycle,
		Shared:    n.Shared,
		ResourceGroup: &ResourceGroup{
			Name: n.ResourceGroup.Name,
		},
		CIDR: addrPrefixes[0],
		Tags: found.Tags,
	}, nil
}

func (n *VirtualNetwork) Normalize(c *fi.CloudupContext) error {
	c.T.Cloud.(azure.AzureCloud).AddClusterTags(n.Tags)
	return nil
}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Use a VNet with exactly one address prefix for the cluster
2. Or let kOps create its own VNet instead of specifying an existing NetworkID
3. Adjust the VNet address prefixes in Azure before importing

When it happens

Trigger: Thrown at upup/pkg/fi/cloudup/azuretasks/virtualnetwork.go:87 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/db519d39848c03b7. Report an issue: GitHub.