When you enter your optifine details, is there a yellow box for where the email goes? Like this? Sometimes when it's like that, the login fails for me.
I noticed also that the capes were gone today. I don't know if it's just a hiccup in their system, but if it's a EULA related thing, well one of the most popular Minecraft mods has gone down the drain.
First things first, please do not necropost (post on old threads). None the less, I'll help you. You should read the error message, the authentication service that requires login validation on the OptiFine website is probably down or has issues. Changing your password won't help you.
i'm getting mad i just got a cape yesterday but each time it get the username and password wrong too many times it doubles the time. and i'm at 80 Min i'm in minecraft 1.11 optifine and want to change my cape. im emailing him but hes no relpying.
For all the users who has an problem with this now type your gmail down not take that like its yellow in the gmail box then it will help