I've been having a really tough time upgrading from 7.1 to 7.5 on my external connection server, the internal connection server works fine. I think the breakdown is on the LDAP sync beacuse that is usually where it fails plus i found this in the logs:
Property(C): LDAP_UPGRADE_ERROR_MESSAGE1 = LDAP is not ready for an upgrade. Error in reaching the server [VDM_LDAP_ERROR_SERVER_NAME] to get replication status. Please resolve the issue and try again. To get more information, run the command "repadmin /showrepl [VDM_LDAP_ERROR_SERVER_NAME]:389"
I did however upgrade to 7.1 > 7.4 and then to 7.5 that worked fine and everything is up and running now. Has anyone had this issue? I have logged a support case to see what they come back with. The documentation says you can go right from 7.1 > 7.5