Index: src/main/java/org/apache/maven/continuum/web/action/AddProjectGroupAction.java
===================================================================
--- src/main/java/org/apache/maven/continuum/web/action/AddProjectGroupAction.java	(revision 541151)
+++ src/main/java/org/apache/maven/continuum/web/action/AddProjectGroupAction.java	(working copy)
@@ -67,6 +67,9 @@
         {
             addActionError( "projectGroup.error.groupId.required" );
         }
+        else if ( groupId != null && groupId.trim().equals( "" ) ) {
+            addActionError( "projectGroup.error.groupId.cannot.be.spaces" );
+        }
     }
 
     public String execute()
Index: src/main/resources/localization/Continuum.properties
===================================================================
--- src/main/resources/localization/Continuum.properties	(revision 541151)
+++ src/main/resources/localization/Continuum.properties	(working copy)
@@ -151,6 +151,7 @@
 projectGroup.error.name.cannot.be.spaces = Project Group Name cannot contain spaces only.
 projectGroup.error.name.already.exists = Project Group Name already exists.
 projectGroup.error.groupId.required = Project Group ID required.
+projectGroup.error.groupId.cannot.be.spaces = Project Group ID cannot contain spaces only.
 
 # ----------------------------------------------------------------------
 # Page: Edit Project Group