@@ -12,6 +12,7 @@ import (

 	"github.com/docker/docker/api/types/backend"

 	"github.com/docker/docker/builder"

 	"github.com/docker/docker/builder/dockerignore"

+	"github.com/docker/docker/errdefs"

 	"github.com/docker/docker/pkg/fileutils"

 	"github.com/docker/docker/pkg/urlutil"

 	"github.com/moby/buildkit/frontend/dockerfile/parser"

@@ -34,8 +35,9 @@ func Detect(config backend.BuildConfig) (remote builder.Source, dockerfile *pars

 	case remoteURL == ClientSessionRemote:

 		res, err := parser.Parse(config.Source)

 		if err != nil {

-			return nil, nil, err

+			return nil, nil, errdefs.InvalidParameter(err)

 		}

+

 		return nil, res, nil

 	case urlutil.IsGitURL(remoteURL):

 		remote, dockerfile, err = newGitRemote(remoteURL, dockerfilePath)

@@ -106,7 +108,7 @@ func newURLRemote(url string, dockerfilePath string, progressReader func(in io.R

 	switch contentType {

 	case mimeTypes.TextPlain:

 		res, err := parser.Parse(progressReader(content))

-		return nil, res, err

+		return nil, res, errdefs.InvalidParameter(err)

 	default:

 		source, err := FromArchive(progressReader(content))

 		if err != nil {

@@ -146,11 +148,17 @@ func readAndParseDockerfile(name string, rc io.Reader) (*parser.Result, error) {

 	br := bufio.NewReader(rc)

 	if _, err := br.Peek(1); err != nil {

 		if err == io.EOF {

-			return nil, errors.Errorf("the Dockerfile (%s) cannot be empty", name)

+			return nil, errdefs.InvalidParameter(errors.Errorf("the Dockerfile (%s) cannot be empty", name))

 		}

 		return nil, errors.Wrap(err, "unexpected error reading Dockerfile")

 	}

-	return parser.Parse(br)

+

+	dockerfile, err := parser.Parse(br)

+	if err != nil {

+		return nil, errdefs.InvalidParameter(errors.Wrapf(err, "failed to parse %s", name))

+	}

+

+	return dockerfile, nil

 }

 func openAt(remote builder.Source, path string) (driver.File, error) {