tmpfs options are incompatible with type npipe

Error message

tmpfs options are incompatible with type npipe

What it means

Returned by handleNpipeToMount (cli/compose/convert/volume.go:184-185). tmpfs options (size) describe an in-memory filesystem and are meaningless for a named-pipe forward, so the converter rejects a `tmpfs:` block on an npipe entry. (A `bind:` block is allowed on npipe; tmpfs is not.)

Solutions

Remove the `tmpfs:` options block from the npipe entry.
If a size-capped in-memory filesystem was intended, change `type:` to `tmpfs` (no source).

Example fix

# before
volumes:
  - type: npipe
    source: \\.\\pipe\\engine
    target: \\.\\pipe\\engine
    tmpfs:
      size: 67108864

# after
volumes:
  - type: npipe
    source: \\.\\pipe\\engine
    target: \\.\\pipe\\engine

Defensive patterns

Strategy: validation

Validate before calling

for i, v := range serviceVolumes {
    if v.Type == "npipe" && v.Tmpfs != nil {
        return fmt.Errorf("service volume[%d] target=%q: type npipe must not declare a tmpfs block", i, v.Target)
    }
}

Try / catch

mounts, err := convert.Volumes(serviceVolumes, stackVolumes, namespace)
if err != nil && strings.Contains(err.Error(), "tmpfs options are incompatible with type npipe") {
    return fmt.Errorf("compose config error: %w (remove the tmpfs: block from the npipe entry)", err)
}

Prevention

Do not carry a tmpfs block onto an npipe entry; the two are unrelated.
Keep option blocks aligned with the volume's declared type.

When it happens

Trigger: ServiceVolumeConfig with Type=="npipe" and Tmpfs!=nil passed to convertVolumeToMount().

Common situations: Switching a tmpfs entry to npipe and leaving `tmpfs: { size: ... }` behind; YAML merge bringing in tmpfs options.

Related errors

AI-assisted analysis of docker/cli@4f84911bfe (2026-08-07). Data as JSON: /api/errors/69d8b4a95d174e65. Report an issue: GitHub.

Appendix: source

Thrown at cli/compose/convert/volume.go:185

		}
	}
	return result, nil
}

func handleNpipeToMount(volume composetypes.ServiceVolumeConfig) (mount.Mount, error) {
	result := createMountFromVolume(volume)

	if volume.Source == "" {
		return mount.Mount{}, errors.New("invalid npipe source, source cannot be empty")
	}
	if volume.Volume != nil {
		return mount.Mount{}, errors.New("volume options are incompatible with type npipe")
	}
	if volume.Image != nil {
		return mount.Mount{}, errors.New("image options are incompatible with type npipe")
	}
	if volume.Tmpfs != nil {
		return mount.Mount{}, errors.New("tmpfs options are incompatible with type npipe")
	}
	if volume.Bind != nil {
		result.BindOptions = &mount.BindOptions{
			Propagation: mount.Propagation(volume.Bind.Propagation),
		}
	}
	return result, nil
}

func handleClusterToMount(
	volume composetypes.ServiceVolumeConfig,
	stackVolumes volumes,
	namespace Namespace,
) (mount.Mount, error) {
	if volume.Source == "" {
		return mount.Mount{}, errors.New("invalid cluster source, source cannot be empty")
	}
	if volume.Tmpfs != nil {

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