How do I resolve an unnamed requirements problem during an update?
Since the database information was transferred into a new settings.php file instead of keeping the old one, it is possible that the the custom value for the path to the synch configuration directory is not found.

Reference: Upgrading Drupal

Look for the code:

$config_directories['sync'] = 'sites\default\files\your-config-folder


in the settings.php file &amp; update it to match the address on your web server.

"This solution worked for me.
In order to find that config_gobblygook, I looked in docroot/sites/default/files and in there is a folder named config_ and then a whole bunch of letters and numbers. I copied that full name and then inserted it into line 247 of the settings.php file."

The same problem is described here with a similar solution.

Related: 


Changing the storage location of the sync directory
How do I fix this Configuration Directory sync error?


Otherwise make sure the most recent nginx.conf file for Drupal is in use, as there have been changes to that to fix the update.php issue. See:


web /update.php sequence does not work with Drupal 8
Drupal 8 Nginx configuration on Homestead (update.php works ok)
Latest Version - NGINX