diff --git a/app/assets/javascripts/app/controllers/_ui_element/datetime.coffee b/app/assets/javascripts/app/controllers/_ui_element/datetime.coffee
index 648aa9981..4e6c5ba5f 100644
--- a/app/assets/javascripts/app/controllers/_ui_element/datetime.coffee
+++ b/app/assets/javascripts/app/controllers/_ui_element/datetime.coffee
@@ -37,6 +37,7 @@ class App.UiElement.datetime extends App.UiElement.basedate
   @buildTimestamp: (currentInput) ->
     timestamp = "#{currentInput[0]}T#{currentInput[1]}:00.000Z"
     time = new Date( Date.parse(timestamp) )
+    return '' if isNaN time
     time.setMinutes( time.getMinutes() + time.getTimezoneOffset() )
     @log 'setNewTime', time.toString()
     time.toISOString().replace(/\d\d\.\d\d\dZ$/, '00.000Z')
diff --git a/public/assets/tests/form_validation.js b/public/assets/tests/form_validation.js
index 1a4291130..08876a344 100644
--- a/public/assets/tests/form_validation.js
+++ b/public/assets/tests/form_validation.js
@@ -309,6 +309,10 @@ test( "datetime selector check", function() {
   }
   deepEqual(params, test_params, 'params check')
 
+  // Regression test for issue #2173 - Invalid date causes errors
+  el.find('.js-datepicker').datepicker('setDate', '01/01/99999')
+  el.find('.js-datepicker').datepicker('setDate', '01/01/1ABCDEFG')
+  el.find('.js-datepicker').datepicker('setDate', '01/01/1äöüß')
 });
 
 test( "date selector check", function() {