Symptoms

Can not deploy workflows onto any K2 Environments, get error Primary Credentials not authenticated. Connection string test will work in K2 for Visual Studio but when clicking okay to change server connection we receive error.
 

Diagnoses

No connection can be made to the K2 Dev or Prod environments through K2 Studio or K2 Designer for Visual Studio. In K2 Object browser for visual studio we also see in the environments tab that it is trying to connect but can not.

Attempted to do a runas /user:domainuser /netonly "C:Program Files (x86)K2 blackpearlK2StudioK2Studio.exe" with the user credentials for one of the given accounts that has permissions on the K2 Server. This did not have an impact, same error still occurs. When trying to connect to a K2 server on a separate domain this "run as" command will run visual studio as the local domain user but when making calls to the K2 Host Server it will do the calls as the K2 account we added in the command. It was thought that the issue was that it was not using the correct user when trying to make the connection to K2 from a separate domain. Even when running as an account that has admin permissions this did not change the issue.
 

Resolution

After restarting the K2 Blackpearl Server service and doing some testing this solved the issue. Users could now make a connection to the environments through K2 Studio and K2 Designer for Visual Studio.