docker/cli · error · invalidParameter

conflicting options: cannot specify both --link and per-netw

Error message

conflicting options: cannot specify both --link and per-network links

What it means

Raised in applyContainerOptions (opts.go:815) when container links are given both with the top-level --link flag and inside the advanced per-network syntax (--network name=...,link=...). The two notations target the same endpoint field, so combining them is ambiguous and rejected.

Source

Thrown at cli/command/container/opts.go:816

			if ep == nil || reflect.ValueOf(*ep).IsZero() {
				continue
			}
		}
		endpoints[n.Target] = ep
	}
	if hasUserDefined && hasNonUserDefined {
		return nil, invalidParameter(errors.New("conflicting options: cannot attach both user-defined and non-user-defined network-modes"))
	}
	return endpoints, nil
}

func applyContainerOptions(n *opts.NetworkAttachmentOpts, copts *containerOptions) error { //nolint:gocyclo
	// TODO should we error if _any_ advanced option is used? (i.e. forbid to combine advanced notation with the "old" flags (`--network-alias`, `--link`, `--ip`, `--ip6`)?
	if len(n.Aliases) > 0 && copts.aliases.Len() > 0 {
		return invalidParameter(errors.New("conflicting options: cannot specify both --network-alias and per-network alias"))
	}
	if len(n.Links) > 0 && copts.links.Len() > 0 {
		return invalidParameter(errors.New("conflicting options: cannot specify both --link and per-network links"))
	}
	if n.IPv4Address.IsValid() && copts.ipv4Address != nil {
		return invalidParameter(errors.New("conflicting options: cannot specify both --ip and per-network IPv4 address"))
	}
	if n.IPv6Address.IsValid() && copts.ipv6Address != nil {
		return invalidParameter(errors.New("conflicting options: cannot specify both --ip6 and per-network IPv6 address"))
	}
	if n.MacAddress != "" && copts.macAddress != "" {
		return invalidParameter(errors.New("conflicting options: cannot specify both --mac-address and per-network MAC address"))
	}
	if len(n.LinkLocalIPs) > 0 && copts.linkLocalIPs.Len() > 0 {
		return invalidParameter(errors.New("conflicting options: cannot specify both --link-local-ip and per-network link-local IP addresses"))
	}
	if copts.aliases.Len() > 0 {
		n.Aliases = make([]string, copts.aliases.Len())
		copy(n.Aliases, copts.aliases.GetSlice())
	}
	// For a user-defined network, "--link" is an endpoint option, it creates an alias. But,

View on GitHub (pinned to e9452d6e78)

Solutions

1. Use only the per-network form: --network name=mynet,link=db:db and drop --link
2. Or keep --link and use a plain --network mynet without per-network links
3. Prefer replacing links entirely with network aliases and DNS on a user-defined network, since --link is legacy

Example fix

// before
docker run --link db --network name=appnet,link=cache nginx
// after
docker run --network name=appnet,link=db,link=cache nginx

When it happens

Trigger: `docker run --link db:db --network name=mynet,link=other ...` — copts.links non-empty while the parsed NetworkAttachmentOpts also has Links; validated when the legacy flags are applied to the first --network entry.

Common situations: Legacy scripts using --link (a deprecated bridge-network feature) being migrated to user-defined networks with advanced --network options, leaving the old flag in place.

Related errors

• conflicting options: cannot specify both --network-alias and
• conflicting options: cannot specify both --ip and per-networ
• conflicting options: cannot specify both --ip6 and per-netwo
• conflicting options: cannot specify both --mac-address and p
• conflicting options: cannot specify both --link-local-ip and

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/599beab51b945016.json. Report an issue: GitHub.