We have a single server all in one sas installation (SAS BI server 9.4 M4 )on windows.
For accessing the stored process the following link is used
http://hostname/SASLogon/login?service=http%3A%2F%2Fhostname%2FSASStoredProcess%2Fj_spring_cas_security_check
some times, on rare occasion,users get a log on failure.
Which log to check (in addition to metadata server and object spawner log)