lima-vm/lima · error

failed to convert image to raw: %w

Error message

failed to convert image to raw: %w

What it means

During fetch, the downloaded image's format did not match the supported formats, so ensureRawInCache was invoked to convert it to raw; that conversion failed, and the underlying error is wrapped with this message. The download cannot satisfy the caller's format requirement.

Source

Thrown at pkg/downloader/downloader.go:437

	}

	// If the driver cannot use the format we just downloaded, save a converted
	// raw copy at <shad>/imgconv/raw, keeping the original <shad>/data as-is.
	//
	// Gated on WithImageFormats() (the caller's signal that this is a VM disk
	// image) and on the file not being an ISO 9660 image.
	if len(o.supportedImageFormats) > 0 {
		isISO, err := iso9660util.IsISO9660(shadData)
		if err != nil {
			logrus.WithError(err).Debugf("Skipping cache image conversion for %q (unable to check ISO9660)", shadData)
		} else if !isISO {
			format, err := nativeimgutil.DetectFormat(shadData)
			if err != nil {
				logrus.WithError(err).Debugf("Skipping cache image conversion for %q (unable to detect format)", shadData)
			} else if !slices.Contains(o.supportedImageFormats, format) {
				converted, rawDigest, err := ensureRawInCache(ctx, shadData, format, o.expectedDigest)
				if err != nil {
					return nil, fmt.Errorf("failed to convert image to raw: %w", err)
				} else if converted != "" {
					shadData = converted
					if o.expectedDigest != "" {
						o.expectedDigest = rawDigest
					}
				}
			}
		}
	}

	// no need to pass the digest to copyLocal(), as we already verified the digest
	if err := copyLocal(ctx, localPath, shadData, ext, o.decompress, "", ""); err != nil {
		return nil, err
	}
	res := &Result{
		Status:          StatusDownloaded,
		CachePath:       shadData,
		LastModified:    readTime(shadTime),

View on GitHub (pinned to dd909d0973)

Solutions

1. Read the wrapped %w error to identify the conversion failure root cause (missing tool vs disk space).
2. Free space in the cache directory (df -h; prune ~/.cache/lima).
3. Install/repair the image conversion backend (e.g. qemu-img) or download an image already in the supported raw format.

Example fix

// before: conversion fails because qemu-img missing
$ brew install qemu   # or apt install qemu-utils
// then retry the download; conversion succeeds

if format, err := nativeimgutil.DetectFormat(localFile); err == nil && !slices.Contains(supportedFormats, format) {
    log.Warnf("image %s (%s) will require raw conversion", localFile, format)
}

res, err := d.Download(ctx, local, url)
if err != nil && strings.Contains(err.Error(), "failed to convert image to raw") {
    // inspect wrapped cause; free cache space or install converter, then retry
}

When it happens

Trigger: Download of a qcow2/vdi/etc image where nativeimgutil.DetectFormat succeeds but the format is unsupported, and ensureRawInCache fails (disk full during conversion, DiskUtil.Convert error, unsupported source format for the converter).

Common situations: Downloading VM images that need qemu-img-style conversion on hosts lacking the backing tool (e.g. qemu-img not installed or virtualization framework restrictions); cache dir out of space.

Related errors

• failed to convert %q to raw: %w
• caching-only mode requires the cache directory to be specifi
• invalid digest in raw digest file %q: %w
• failed to read raw digest file %q: %w
• failed to open raw tmp file %q: %w

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/f52ae7a5bcb0a45a. Report an issue: GitHub.