diff --git a/cmd/api-errors.go b/cmd/api-errors.go
index a929da94d..cd0deaa96 100644
--- a/cmd/api-errors.go
+++ b/cmd/api-errors.go
@@ -1526,6 +1526,8 @@ func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
 		apiErr = ErrEntityTooLarge
 	case errDataTooSmall:
 		apiErr = ErrEntityTooSmall
+	case errAuthentication:
+		apiErr = ErrAccessDenied
 	case auth.ErrInvalidAccessKeyLength:
 		apiErr = ErrAdminInvalidAccessKey
 	case auth.ErrInvalidSecretKeyLength: