hallo, I decided to test the upgrade in my only nextcloud installation and I don’t have any backup.
I have this message:
Check for expected files
The following extra files have been found:config.php
At the moment I can’t do any backup, neither make a new installation for testing purposes.
Should I delete the config.php file with all its settings?
Giacomo
I had the same issue with a second nextcloud.log file.
The original and used config.php is located in /var/www/nextcloud/config .
If you have the file somewhere else in the nextcloud folder you could move it somewhere outside /delete it and try the update again.
Edit: you can use find . -name “config.php” in the /var/www/nextcloud folder.
I’ve got results in /config ; /apps/files_external/lib/config.php and /apps/gallery/controller/config.php
So i guess that are the valid locations for the config.php file, since my update worked with these.
In which (sub)folder is this config.php? Normally there should be only one in your_nextcloud_directory/config/ which should be accepted by the installer. Maybe you copied that once to another place as backup or something?
If this is really your used config.php in /nextcloud/config then backup it somewhere first or at least store it’s content somewhere. But without it the nextcloud web page should not load, so I guess the problematic config.php is a copy in another path ;).
€: Ah yes what Michael_C sais 
Michael_C and Michaing, you both where right, like Sherlock Holms.
May be I made a copy of the current config.php file outside its folder and I forgot it.
The update procedure is going ahead, with no problems (till now).
THANKS !