I’ve recently did some quick and dirty installation of K2 4.6.11 on Server 2008 (non R2) hence all you have there is PoSh 2.0 it is not possible to use amazing K2Field.PreReq script to take care about all the prerequisites (it will work for server 2012-2016). So I just went ahead and tried to satisfy complaints from K2 blakcpearl setup manager as I go adding IIS along with KB980368 as indicated by Setup Manager. Alas after installing I was not able to access K2 Workspace with the following error:
“You are not authorized to view this page due to invalid authentication headers.” Why? Quick check of K2 Workspace site authentication showed that Windows Authentication is missing, while according to K2 documentation (source) K2 Workspace does not function if IIS is not configured correctly. Configure the IIS application pool Managed Pipeline mode setting to Classic and ensure that:
- Windows Authentication is enabled
- Anonymous authentication is disabled
So I just went ahead and added Windows Authentication role service and all started work correctly after this. It tells us that: A) K2 setup manager created site config file correctly specifying required authentication method, it just was not installed/available B) Not sure why K2 Setup Manager does not have built-in check to flag this at the installation stage. C) Read up documentation carefully, in this case this page.