I upgraded my test FortiGate 60E to 6.0.7 and have been running for a few days now without any of the issues described above. I haven't tested an upgrade of an HA cluster yet though.
[ul]
Two FortiGate-managed FortiAPs (both running 6.0 build 0066) stayed online.
SSLVPN with FortiToken still working fine.
So far, CPU utilization has stayed low and memory utilization is stable at 60% (same as with 6.0.5).[/ul]
Obviously a small sample set, and I'll do a bit more testing on our internal 30E, 61E and 100E and monitor these boards for more results before rolling out to customers.
We'll try tomorrow a triple jump from 5.4.10 to 6.0.7 in order to get FortiGuard Outbreak Prevention and Fortisandbox cloud without limitation in the number of files uploaded. 6.0.8 fixes CVE-2018-9195 and some other bugs as per diff with release notes from 6.0.7 but too young for us to try.
Ok. Upgrade done smoothly of a cluster of two FG100E. Detected immediately that we weren't able to edit existing security profiles from GUI (only from policies), but as usual Google is your friend.