diff --git a/frontend-js/src/main/js/gui/admin/AddProjectDialog.js b/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
index 7b8551647f891357ef55c7ece69a1e43a7cc2375..59a57ee98b003208737cba96ff9ad7fc4dbefb8e 100644
--- a/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
+++ b/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
@@ -1254,7 +1254,7 @@ AddProjectDialog.prototype.onSaveClicked = function () {
 AddProjectDialog.prototype.checkValidity = function () {
   var self = this;
   var isValid = true;
-  var error = "<b>Some data is missing.</b><ul>";
+  var error = "<b>There is problem with input data.</b><ul>";
 
   var mapCanvasTypeId = self.getMapCanvasTypeId();
   if (mapCanvasTypeId === "GOOGLE_MAPS_API") {
@@ -1278,6 +1278,11 @@ AddProjectDialog.prototype.checkValidity = function () {
     error += "<li>projectId can contain only alphanumeric characters and -_</li>";
     isValid = false;
   }
+  if (projectId.length > 255) {
+    error += "<li>projectId must be shorter than 256 characters</li>";
+    isValid = false;
+  }
+
 
   var rootExist = 0, i;
   for (i = 0; i < self.getZipEntries().length; i++) {