Symptoms

Federation Sign-in Error.
The K2 App is installed and working on O365, but only for the person that installed it. While the cert, trusted sites and group permissions as well as workspace permissions have been updated, other users receive the attached two errors.
K2TSTS10002: An error occurred while processing a WS-Federation sign-in response
AADSTS50105: The signed in user ‘âUser Email]’ is not assigned to a role for the application ‘iDomain]’
 

Diagnoses

The error was caused by mismatch version of K2 for SharePoint app.
 

Resolution

After follow the steps on how to replace the K2 for SharePoint App from the following KB, http://help.k2.com/kb001671 to replace the correct version of K2 for SharePoint app for SharePoint Online (4.4120.5.1), the issue was resolved