What causes "failed to create ASIF image %#q: %w" in lima-vm/lima?

Check the wrapped diskutil error (stderr) for the underlying cause (space, permissions, unsupported format)

failed to create ASIF image %#q: %w

Error message

failed to create ASIF image %#q: %w

What it means

NewASIF creates a blank ASIF disk image by shelling out to `diskutil image create blank --format ASIF` on macOS. This error wraps a non-zero exit from diskutil during creation. It means diskutil refused or failed to create the image file at the requested path/size.

Source

Thrown at pkg/imgutil/nativeimgutil/asifutil/asif_darwin.go:24

import (
	"bytes"
	"context"
	"encoding/xml"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"strconv"
	"strings"

	"github.com/lima-vm/lima/v2/pkg/plist"
)

// NewASIF creates a new ASIF image file at the specified path with the given size.
func NewASIF(path string, size int64) error {
	createArgs := []string{"image", "create", "blank", "--fs", "none", "--format", "ASIF", "--size", strconv.FormatInt(size, 10), path}
	if err := exec.CommandContext(context.Background(), "diskutil", createArgs...).Run(); err != nil {
		return fmt.Errorf("failed to create ASIF image %#q: %w", path, err)
	}
	if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
		if _, err2 := os.Stat(path + ".asif"); !errors.Is(err2, os.ErrNotExist) {
			// diskutil may create the file with .asif suffix
			if err3 := os.Rename(path+".asif", path); err3 != nil {
				return fmt.Errorf("failed to rename ASIF image from %#q to %#q: %w", path+".asif", path, err3)
			}
		}
	}
	return nil
}

// NewAttachedASIF creates a new ASIF image file at the specified path with the given size
// and attaches it, returning the attached device path and an open file handle.
// The caller is responsible for detaching the ASIF image device when done.
func NewAttachedASIF(path string, size int64) (string, *os.File, error) {
	if err := NewASIF(path, size); err != nil {
		return "", nil, err

View on GitHub (pinned to dd909d0973)

Solutions

Check the wrapped diskutil error (stderr) for the underlying cause (space, permissions, unsupported format)
Verify the macOS version supports `diskutil image create blank --format ASIF` (try the command manually)
Free disk space or reduce the requested image size
Choose a writable, simple path without special characters

Example fix

// diagnose manually
// before: opaque failure from NewASIF
// after
err := asifutil.NewASIF(path, size)
if err != nil {
    log.Fatalf("ASIF creation failed; run: diskutil image create blank --fs none --format ASIF --size %d %q", size, path)
}

Defensive patterns

Strategy: try-catch

Validate before calling

// preflight: check host free space and diskutil ASIF support
if st, err := os.Stat(filepath.Dir(path)); err != nil || st.Mode().Perm()&0o200 == 0 { return errors.New("image directory not writable") }

Try / catch

if err := asifutil.NewASIF(path, size); err != nil {
    var exitErr *exec.ExitError
    if errors.As(err, &exitErr) { log.Printf("diskutil failed: %s", exitErr.Stderr) }
    return err
}

Prevention

Free disk space before creating large images
Confirm macOS supports ASIF diskutil image subcommands
Use simple, writable paths for disk images

When it happens

Trigger: Calling NewASIF(path, size) (via createDiskMacOSGuest or NewAttachedASIF) when diskutil fails: unsupported macOS version lacking ASIF support, insufficient disk space for the requested size, unwritable target path, or invalid size argument.

Common situations: Running on macOS older than the version that supports ASIF images (Tahoe/26+ era diskutil); creating huge images on a nearly full APFS volume; path in a read-only location or with characters diskutil dislikes.

Related errors

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/848f1a1d80f17d2c. Report an issue: GitHub.