@@ -725,10 +725,12 @@ func postContainersStart(eng *engine.Engine, version version.Version, w http.Res

 	// allow a nil body for backwards compatibility

 	if r.Body != nil {

-		if api.MatchesContentType(r.Header.Get("Content-Type"), "application/json") {

-			if err := job.DecodeEnv(r.Body); err != nil {

-				return err

-			}

+		if !api.MatchesContentType(r.Header.Get("Content-Type"), "application/json") {

+			return fmt.Errorf("Content-Type is not supported: %s", r.Header.Get("Content-Type"))

+		}

+

+		if err := job.DecodeEnv(r.Body); err != nil {

+			return err

 		}

 	}

 	if err := job.Run(); err != nil {