After an update, I try to go to the Helm login screen and get the following .NET error:
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
Parser Error Message: Could not load file or assembly 'WHA.Registry, Version=126.96.36.199, Culture=neutral, PublicKeyToken=f759a0c34c27cfd7' or one of its dependencies. The system cannot find the file specified.
This suggests the registry components have not updated properly.
All you need to do is go to the Helm Configuration Tool and go to the Software Updates tab. Then click the Helm Components tab on that screen, and click the Reinstall Components button.
After the components are reinstalled, try the control panel again. You may get a message about the Helm Update being in progress.
If this is the case, go to
[HELM INSTALL FOLDER\WebHost Automation\Helm4\ControlPanel
and delete the UpdateInProgress file.
The control panel login screen should now work.