Index: management/univention-management-console-module-ucr/umc/js/ucr.js
===================================================================
--- management/univention-management-console-module-ucr/umc/js/ucr.js	(Revision 72878)
+++ management/univention-management-console-module-ucr/umc/js/ucr.js	(Arbeitskopie)
@@ -77,7 +77,11 @@
 				type: TextBox,
 				name: 'key',
 				description: _( 'Name of UCR variable' ),
-				label: _( 'UCR variable' )
+				label: _( 'UCR variable' ),
+				invalidMessage: _( 'A valid key must contain at least one character and can only contain letters, numerals, and "/", ".", "_", "-".' ),
+				validator: function (value, constraints) {
+					return !!value && !/[^a-zA-Z0-9/._-]/.test(value);
+				}
 			}, {
 				type: TextBox,
 				name: 'value',
@@ -105,8 +109,10 @@
 				label: _( 'Save' ),
 				style: 'float: right',
 				callback: lang.hitch(this, function() {
-					this._form.save();
-					this.hide();
+					if (this._form.getWidget('key').isValid()) {
+						this._form.save();
+						this.hide();
+					}
 				})
 			}, {
 				//FIXME: Should be much simpler. The key name should be enough