Community Auth - a database error when logging in

When I use your session config, all is working fine. This is on Ubuntu 16.04 with PHP7.

What is the value of your encryption key? Mine in example is like this:

PHP Code:

$config['encryption_key'] = hex2bin('5d3a06b1a1efeb861ad761fb8839794f'); 


I don't know that nginx would have anything to do with it, but my experience with it is limited. It's interesting that your session ID is returning NULL.  I suppose you'd have to debug that and see what/why/where.

Mine is

Code:

$config['encryption_key'] = hex2bin('31a953d513fa2c32ae58b5520b495745');