When a DNN admin/host (or user with appropriate permissions) log's in, a bar (known as the control panel) appears at the top to allow swift access to common operations. The control panel is configurable and can change, using either alternative implementations shipped with the platform or else 3rd party alternatives such as Advanced Control Panel
As the UI/UX of control panels can often be radically different, during upgrades the existing control panel settings are retained. However over time older control panels, as they get replaced, are regarded as being deprecated. As such they start to get gradually tested less and less, and eventually new issues found in them are unlikely to be fixed. As such site administrators are recommended to use more recent panels, which as well as being tested continue to be developed and improved.
Control panel history
The first implementation of the control panel was known as "ICONBAR" -this was introduced in 2004/2005 with the DNN 3.0 release. This was later replaced with the “RIBBONBAR” controlpanel (in April 2010), followed by the “CONTROLBAR” panel shipped with DNN 7.0.0.
If a site is still using "ICONBAR" and upgrades to DNN 7.2.0 or above, they will find that clicking the admin or host links no longer works. At present there is no plan to fix this issue, so the correct resolution is to use one of the other control panels such as ribbonbar or controlbar (controlbar is the recommended option)
To do this in advance of an upgrade is easy, and can be done via the UI - please see here
For sites that have already upgraded and are seeing problems, they can resolve this issue by running the following SQL statement:
UPDATE hostsettings set SettingValue='Admin/ControlPanel/ControlBar.ascx' where SettingName='ControlPanel'
Note: you’ll have to force an application recycle so DNN can pick up the direct database change (e.g. edit web.config, add a space, delete the space and save).