Your username and password don't match I've tried to log in to my Google Account on my phone and tablet, I've tried on a friends HTC and mine are Samsung. On all the devices, I get "Your username and password don't match" and instructions to reset the password. I have tried countless times, reset the password about 5 times and double checked, even quadruple checked. Tried copying and pasting the password, etc. I have tried logging in on the browsewr, it works fine. I have tried enabling access for less secure apps/devices, still nothing. 2 factor wasn't on, I tried turning it on twice, still nothing. Restarting the phone, checking the date, etc. I have tried signing in with a different Google account on the phone and it works like a charm but mine doesn't. I have been searching for hours, checked numerous Stack Overflow posts, Android Forums, etc. There (should) only be 1 Google Account (well, there isn't any in the settings right now). I think this was working before I factory reset it, but not sure.

TL;DR: Correct password, enabled &amp; disabled less secure apps, tried turning off 2 factor, other account works, tried on other devices. Still nothing.

WTL;DR Not working, tried everything.
Go to your Google account settings from a browser and setup an App Password for the device.  I chose the option "Other..." from the app drop down list so that I could easily identify the device should I decide to revoke it later.

The sign-in problem was due to the Two-Step verification process I had previously setup on my account.