Unable to authenticate to web interface with correct credentials - PROPFIND 404 519

[orquitech]

Hello fellow GitHubbers... I've been trying for 2 days to get a sabre katana installation to work in a Debian 9, PHP 7, Apache2 setup.

I started on the NGINX route and was able to log in to the admin.php interface after adding dav_ext_methods & dav_methods directives to the NGINX config file, however the dashboard and some other features were not available so I figured webDAV and NGINX were not coexisting properly and decided to start over.

Based on the suggestions on the sabre website, I started again all over using Apache this time. Ran into all sort of issues which I was able to sort out (missing php7.0-mbstring, libapache2-mod-php, php-xml, also enabled these modules: a2dismod mpm_prefork, mpm_event, dav, dav_fs, php7.0-fpm and configured /dav_fs.conf, etc).

I was then getting this error:
##Error:PHP Fatal error: Uncaught PDOException: SQLSTATE[HY000] [1045]
Which I solved by changing the root password in MySQL

I was feeling lucky enough after solving a few issues here and there, but unfortunately I've just hit a snag and have spent half a day looking for a solution but I can't find one.

My most present unsolved issue:

I am able to browse to the admin.php web page and I am able to input credentials. However...

If I use the right credentials: Firefox receives a PROPFIND 404 'Not Found'
If I use wrong credentials: Firefox receives a PROPFIND 401 'Unauthorized'

The above test, makes me feel 100% sure I am using the right credentials, however the result is the same, I receive "Invalid credentials Either username or password is invalid."

When checking Apache access log I find the following:

• admin [10/Jan/2019:19:15:05 -0500] "PROPFIND /server.php/system HTTP/1.1" 404 519 "http://XX.XX.XX.XX/admin.php"

Can anyone please shed some light here?, please guide me guys

Thanks