The type initializer for "DocuWare.MessageBus.Model.Configuration.DefaultHyperBusFactory" threw an exception

Behavior:

When starting Web Client or when trying to log in to Docuware Platform following error is shown in browser:
The request could not be served.
500 - The Type Initializer for "DocuWare.MessageBus.Model.Configuration.DefaultHyperBusFactory" has caused an exception.

Solution:

Starting with DocuWare 6.9 the DocuWare Services and the DocuWare Application Pools are runnin with the same user. This user is typically specified during installation and is add to the local group of administrators.
During an upgrade the Setup doesn't verify wether the user is already in that group. So please make sure that the user is in the local group of administrators. The error will disappear then.