After integrating Oracle E-Business Suite with SSO, setting the system profile 'Applications SSO Auto Link User' = 'Enabled' lets users login to Oracle using only their SSO username/pwd (Windows NT username/pwd) if the 3rd party LDAP directory is MS Active Directory) WITHOUT the need to enter their Oracle E-Business local username/pwd again in the next page. This profile 'automatically links' the Windows NT username and the existing Oracle username internally (provided there is a user_name in FND_USER that EXACTLY matches the Windows NT username) and directly shows the Oracle E-Business responsibilities navigation pane. It does it by updating FND_USER.USER_GUID to a value that matches with the corresponding OID's ORCLGUID value of the logged in user.
Due to some circumstances, one may have to bulkdelete all the OID users and reload them from AD to OID using the bootstrap process. Because it is a new bootstrap process, a new ORCLGUID may get generated in the OID that will make it out of sync with the target FND_USER.USER_GUID value. With such a scenario, Oracle will prompt again for the E-Business local username/pwd despite the system profile 'Applications SSO Auto Link User' having an 'Enabled' value. One can verify the mismatch after the reload by running the following command.
ldapsearch -v -h oid_host_name -p 389 -D "cn=orcladmin" -w ***** -b "" -s sub "sn=RAMINENI*" uid orclguid orclactivestartdate orclactiveenddate orclisenabled
ldap_open( oid_host_name, 389 )
This orclguid shown above may NOT match the FND_USER.USER_GUID for the same user because the former is a newly generated one because of the reload process. In this case, Oracle prompts for the Oracle E-Business username/pwd after entering the Windows NT username/pwd in the login page even though the system profile 'Applications SSO Auto Link User' is set to 'Enabled', often confusing the user.
The process to 'auto link' SSO username and the FND_USER user_name after a reload of data from the 3rd party LDAP directory to OID is to update FND_USER.USER_GUID value to NULL.