diff --git a/loopback/common/models/vn-model.js b/loopback/common/models/vn-model.js
index f56183df2..cc3eede8e 100644
--- a/loopback/common/models/vn-model.js
+++ b/loopback/common/models/vn-model.js
@@ -145,9 +145,15 @@ module.exports = function(Self) {
         rewriteDbError(replaceErrFunc) {
             function replaceErr(err, replaceErrFunc) {
                 if (Array.isArray(err)) {
+                    const errors = err.filter(error => {
+                        return error != undefined && error != null;
+                    });
                     let errs = [];
-                    for (let e of err)
-                        errs.push(replaceErrFunc(e));
+                    for (let e of errors) {
+                        if (!(e instanceof UserError))
+                            errs.push(replaceErrFunc(e));
+                        else errs.push(e);
+                    }
                     return errs;
                 }
                 return replaceErrFunc(err);