You'll need at least ViewParticipate permissions on the process (and then of course you will need to have participated), but 404 is a standard HTTP response code indicating that the client was able to communicate with the server but the server could not find the requested page.

Could you provide some additional info like which version of K2 you're running, from where are you launching Viewflow, etc.

Thank you.

I now find out, that this is a problem with my account only. This link should start the reporting service and the process overview of the running process (I did'nt know what should happend).

My account can't start the reporting service from K2 Workspace - but it is a K2 Admin with View permissions.

I think it is a problem of too much membership in AD Groups - I had this also with other programms.