This was a third time this month.
As far as I can tell the log-in username is now case sensitive. Your browser's auto-fill / remember password feature is probably offering a lower case username which was accepted before the website update.
That worked for me on the third attempt...
I have to try that when this happens again
Hmm, I think I only needed to do it once so far, do you keep forgetting your password?
No one else is using this machine, so the browser (Firefox) supplies it. It has a good memory.
By the way, everything has been working several days now. Good.
Getting better. The website asked my password and I could log in without problems.