So I've seen a similar issue floating around with no real solution. In my scenario, however, I do not see any impeding factors as there could have been in other cases.
I am running a couple of ESXi hosts inside VMWare Workstation (on a Dell Poweredge R620). Using ESXi version 6.5 build 4564106. After a clean install of the hosts the root password works for a little bit, but then all the sudden stops working everywhere - web, direct console or ssh. If I reset the settings via the console (when it wants to let me in), which resets the root password to blank, everything works dandy, except that do deploy VCSA I need root to have a password. It also works sometimes but no others. At one point, SSH was working on one host, but not console access... It's like it has moods...
The hosts are not publicly facing and are exclusively on my local network (hence no root login attempts so it locks out). I've tried setting the password inside the console and via the web interface. The keyboard layout set in the console is US Default. My password contain only alphanumeric characters with a single capital alpha character. I've also tried adding an exclamation mark to the password to no avail. The exact error message in the console is "Invalid username or password". DCU timeout are disabled (set to 0). Finally, yes I type in the password slowly and deliberately.
Either I missed some sort of critical configuration or its a bug in ESXi.
~confuded
