Checkmk Werk 15813: Clarify combined graph dashlet error message for filtered boards

ID: 15813 Title: Clarify combined graph dashlet error message for filtered boards Component: Multisite Level: 1 Class: Bug fix Version: 2.3.0b1 As of publishing of this Werk, the combined graph dashlet (as used in the Main Dashboard) does not yet support filtering. The corresponding error message was updated to better inform the user about that fact.