No problems. So you're version is pretty recent. Humm ... very odd (especially the "all of a sudden breaking" part).
OK so ... interesting question (to help get a bit more information perhaps) -- turn on account auditing on the DC when you re-try that ... that MAY give us a bit more information as to why the domain join failed.
GOTCHA -- essentially, we can only report "hey - it failed", since (really annoyingly) there's not a lot of information for reasons for failure (I suspect mainly a security precaution).
SO you may have to enable account auditing on a DC to see "its side of the story" (/get a few more bread crumbs as to what's going on).
Couple of things to think about:
- Did the DC('s) get patched recently? Possible that one of the more recent Microsoft patches changed something?
That may not HELP necessarily right away, but at least it should make sense of things WHY it happened "all of a sudden" & will help with the duplication (may even be down to DC Windows version?) . - See what the DC-side account auditing has to say. Essentially, we're looking for the reason *WHY* the domain join hasn't worked. Now - word of warning, the "error messages" from account auditing are not SUPERBLY helpful (mildly put), and there's usually some guesswork / psycho-analysis involved as to what the REAL problem is, but at least it gives you a direction to look at.
Having that information should certain help figure out what's ACTUALLY going on, I would hope. - Definitely you're doing the right thing - passwords should be sensitive strings & that stuff needs to work. Since you didn't update the LDMS Core, i *SUSPECT* that it's more likely that a Microsoft patch or something like that performed an environmental change (that's just guessing though), so that's why I suggested the above steps.
Hope that helps you progress this a bit further?