Forticlient 5.4.1 Seems to Break OS X - AD login

[karlkeppner]

About a week ago I upgraded our Fortigate to 5.4 since the client on forticlient.com was 5.4 and when it was installed on new endpoints, it wouldn't register to our 5.2 Fortigate. Easy enough upgrade but a day or so later we started to get Mac users, on El Capitan, that now couldn't log in via AD credentials. We verified that yes, the username and password being used was correct. We tried our domain admin account and still no dice. Every once in a while you can get one to log in but for the most part, nothing. We rebuilt one of the Macs fresh with a brand new copy of Forticlient 5.4.1 from the download link on the dashboard of the Fortigate. Still nothing. We removed Forticlient and everything now works. I had a policy in the Fortigate to update Forticlient on the endpoint version didn't match the Fortigate version. So one by one the Macs have updated and locked users out.

Has anyone else seen this issue or know a fix until it is corrected?

Thanks in advance.