Many times I've seen this and it drives me nuts and would love to see who has a workaround for it. When logging into the FQDN I get a redirect to /ui/api/internal/login/callback. At this point I get a browser error which is different for each browser but is an error none the less.
Chrome:
{"message":"SAML assertion not yet valid"}
Firefox:
I've also see this issue when there is time drift in an environment.
Update:
I was able to get into SDDC Manager by using the following process (still not official root cause):
For some reason if you refresh too quickly or try other things to get into the main URL you will get the white screen.
I've also see this issue when there is time drift in an environment.
I went back and checked on this after your post and it's spot on. I'm syncing everything to the same source but vCenter is slightly out of sync from the hosts and SDDC Manager. When I toggle the VAMI to point to the hosts for NTP instead of external everything is synced up fine. Now off to look at why vCenter is syncing wrong, but this troubleshooting was able to replicate over and over that this is indeed a time drift issue. Thanks as always tenthirtyam
Cool! Thanks for the update barnette08 - always happy to help you and others.