dagger/dagger · error

pushed image is nil

Error message

pushed image is nil

What it means

PushImage guards against being handed a nil image; the pushed img must carry a RootDesc descriptor to construct the push. A nil image indicates a programming error upstream rather than a registry problem.

Source

Thrown at engine/server/resolver/resolver.go:641

	mediaType, err := imageutil.DetectManifestMediaType(ra)
	if err != nil {
		return ocispecs.Descriptor{}, false, err
	}
	return ocispecs.Descriptor{
		Digest:    dgst,
		Size:      ra.Size(),
		MediaType: mediaType,
	}, true, nil
}

func (r *Resolver) PushImage(ctx context.Context, img *PushedImage, ref string, opts PushOpts) (rerr error) {
	span, ctx := tracing.StartSpan(ctx, "pushing "+ref, telemetry.Encapsulated(), telemetry.Encapsulate())
	defer func() {
		tracing.FinishWithError(span, rerr)
	}()

	if img == nil {
		return errors.New("pushed image is nil")
	}

	ctx = contentutil.RegisterContentPayloadTypes(ctx)
	rootDesc := img.RootDesc
	parsedRef, err := reference.ParseNormalizedNamed(ref)
	if err != nil {
		return err
	}
	if opts.ByDigest {
		ref = parsedRef.Name()
	} else {
		refWithDigest, err := reference.WithDigest(reference.TagNameOnly(parsedRef), rootDesc.Digest)
		if err != nil {
			return err
		}
		ref = refWithDigest.String()
	}

View on GitHub (pinned to 82ba2681db)

Solutions

1. Fix the caller to never pass nil: check the image construction error before pushing
2. Add an upstream nil check and return a descriptive error instead of invoking PushImage
3. If the image comes from a build result, verify the publish step actually produced an image

Example fix

// before
img, _ := buildResult.GetImage(ctx)
PushImage(ctx, ref, img)
// after
img, err := buildResult.GetImage(ctx)
if err != nil { return err }
if img == nil { return errors.New("build produced no image") }
PushImage(ctx, ref, img)

if img == nil {
    return errors.New("refusing to push: image is nil (build failed to produce an image?)")
}

When it happens

Trigger: Calling PushImage(ctx, ref, nil) or passing the result of a failed/short-circuited image construction (e.g. a published-image variable that was never populated).

Common situations: Code that constructs an Image via an API whose error was ignored, then pushes the nil result; refactors dropping an early nil check.

Related errors

• encode persisted directory: nil directory
• with file: nil source snapshot
• encode persisted git repository: nil repository
• git bundle is required
• cache volume is nil

AI-assisted analysis of dagger/dagger@82ba2681db (2026-09-05). Data as JSON: /api/errors/9b0bae0d3921e26d. Report an issue: GitHub.