I was able to resolve this without assistance from Customer Service, who replied to my issue report with a notification that it had been reported, after which they marked my issue as "solved".

I manually launched the MTGALauncher.exe application from "C:\Program Files\Wizards of the Coast\MTGA\MTGALauncher"; the program downloaded a required update, after which I was able to log in successfully.

Same error here. Windows 10 PC.
Unable to Login
Authentication failed for <My Username>

Same issue.
It is not a password issue, putting the incorrect password or email shows the correct "invalid email address or password".
From my PC with windows 10

Same issue here on a Mac OS Big Sur 11.4

Unable to Login on PC here

As with so many others, I'm getting "Unable to login: Authentication failed for <username>" on Win 10. Log attached.

BTW - kinda BS to have a "Status" page that says everything is operational when so many people are having problems logging in.

Same Issue with me. I have uninstalled and reinstalled. I am on windows 10.

Hello,

For us to be able to best assist you with Access issues, please submit at: https://mtgarena-support.wizards.com/hc/en-us/requests/new and select 'Access Issue.

Thanks!

Yup, got the same problem with the authentication, tried removing the app then redownloading but still would not work. Using a MacBook Pro on the latest software.

i cant login because it wont let me type or paste my email on the login.

Same issue. I reset my password and everything. It won't log me in.

I play on my smartphone Samsung Galaxy S10+

Same here. I'm on PC with Windows 10.

Getting the message

Unable to Login
Authentication failed for ccc

---

This is on android. I've tried logging out, resetting my phone, and reinstalling the app - nothing works.

I am also getting this issue on my Windows 10 PC.

same.

Same problem here, but I´m using Windows on a PC. I even tried making a new account but got the same message when attempting to log in.

Getting this issue when using the Android app on my Chromebook (Acer Spin 713).

Android Play Store now reports "This app isn't compatible with your device anymore. Contact the developers for more info." -- This started only AFTER the implementation of the new D&D expansion.

WTH?!?!?!

(Still works just fine on my Android smartphone and on my Windows computer, though.)

I'm also having this problem on android this morning. Not sure why it suddenly is doing so, first time I've had any problems with it.

Unable to login on mobile on Android. Looks like lots of people are having this issue under multiple threads. This needs voted and bumped to get their attention.