Page 60 of SO shows the problem management process as a flow chart. The decision "Workaround" has one single exit, which is not labeled. It directly points to "Create Known Error Record". There is no prerequisite for a known error to have a workaround (known error means we know the cause!).
Additionally there is an arrow coming up from resolution back to "Investigation & Diagnosis" and "Workaround?" (it could be that it also points to "Create Known Error Record", since the graph is very ambigous).