After updating to the latest GIt versions (today) using the official upgrade guide and with no errors during the upgrade procedure I can see the login screen just fine.
As soond as I try to login I get this one:

Actual Results:

 >>> UNRECOVERABLE FATAL ERROR <<<

Class PhabricatorAuthPassword contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods    (PhabricatorApplicationTransactionInterface::getApplicationTransactionObject, PhabricatorApplicationTransactionInterface::willRenderTimeline)

/var/www/.../src/applications/auth/storage/PhabricatorAuthPassword.php:3

┻━┻ ︵ ¯\_(ツ)_/¯ ︵ ┻━┻

Expected Results:

Login should work.

PHP Version :

PHP 7.2.19-0ubuntu0.18.04.2 (cli) (built: Aug 12 2019 19:34:28) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies

with Zend OPcache v7.2.19-0ubuntu0.18.04.2, Copyright (c) 1999-2018, by Zend Technologies

Webserver: nginx version: nginx/1.14.0 (Ubuntu)