Nginx is running as www-data, right? Could you paste the output of:
ls -Al /etc/pihole
Thank you jbf for your replay. I just did usermod -aG pihole www-data restarted my webserver and now settings can be saved.
Thank you MichaIng for pointing that out.
Here it is...
root@PanicatTheCisco:~# groups www-data
www-data : www-data pihole
root@PanicatTheCisco:~# ls -Al /etc/pihole
insgesamt 8108
-rw-r--r-- 1 root root 242 Mai 11 13:01 adlists.list
-rwxrwxrwx 1 pihole pihole 242 Mai 11 10:17 adlists.list.old
-rwxrwxrwx 1 pihole pihole 0 Mai 12 06:47 dhcp.leases
-rw-r--r-- 1 pihole pihole 596 Mai 11 13:01 dns-servers.conf
-rw-r--r-- 1 pihole pihole 14 Mai 12 06:48 GitHubVersions
-rw-rw-r-- 1 pihole pihole 5087232 Mai 11 13:02 gravity.db
-rw-r--r-- 1 pihole pihole 1051 Mai 11 13:01 install.log
-rw-r--r-- 1 root root 1100893 Mai 11 13:01 list.0.raw.githubusercontent.com.domains
-rw-r--r-- 1 root root 594672 Mai 11 13:01 list.1.mirror1.malwaredomains.com.domains
-rw-r--r-- 1 root root 521 Mai 11 13:01 list.2.s3.amazonaws.com.domains
-rw-r--r-- 1 root root 43529 Mai 11 13:01 list.3.s3.amazonaws.com.domains
-rw-r--r-- 1 pihole pihole 20 Mai 12 06:50 localbranches
-rw-r--r-- 1 pihole pihole 160 Mai 11 13:02 local.list
-rw-r--r-- 1 pihole pihole 36 Mai 12 06:50 localversions
-rw-r--r-- 1 root root 234 Mai 11 13:01 logrotate
drwxrwxrwx 2 pihole pihole 4096 Mai 11 10:38 migration_backup
-rwxrwxrwx 1 pihole pihole 15 Mai 11 13:01 pihole-FTL.conf
-rwxrwxrwx 1 pihole pihole 1409024 Mai 12 06:53 pihole-FTL.db
-rw-r--r-- 1 pihole pihole 448 Mai 11 13:01 setupVars.conf
-rwxrwxrwx 1 pihole pihole 448 Mai 11 13:01 setupVars.conf.update.bak
Okay, permissions for gravity.db are definitely there and correct.
I just reviewed the Nginx config from docs: Redirecting...
I am not sure whether the basic authentication part could cause problems. Not sure why it is there since the admin panel itself has an included authentication already, so this looks doubled to me? Just to try to comment all lines starting with auth_basic/auth_basic_user_file in your Nginx config, then restart it (systemctl restart nginx) and check if it works. If it still does not, of course revert to re-enable authentication.
I think my config are right, with auth and without auth it doesn't work i tried everything 
server {
listen 80;
listen [::]:80;
root /var/www/html;
server_name panicatthecisco;
autoindex off;
index pihole/index.php index.php index.php index.html index.htm;
location / {
add_header Strict-Transport-Security max-age=15768000;
index index.htm index.html index.php index.nginx-debian.html;
expires max;
try_files $uri $uri/ =404;
}
location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
fastcgi_param FQDN true;
#auth_basic "Restricted"; #For Basic Auth
#auth_basic_user_file /etc/nginx/.htpasswd; #For Basic Auth
}
location /admin {
root /var/www/html;
index index.php index.html index.htm;
#auth_basic "Restricted"; # For Basic Auth
#auth_basic_user_file /etc/nginx/.htpasswd; # For Basic Auth
}
location /*.js {
index index.js;
#auth_basic "Restricted"; #For Basic Auth
#auth_basic_user_file /etc/nginx/.htpasswd; #For Basic Auth
}
location ~ /\.ht {
deny all;
}
}
PHP7.0 is correct, right? Are there any errors in webserver and/or PHP logs:
journalctl -u nginx
journalctl -u php7.0-fpm
tail -20 /var/log/nginx/error.log # Exact path/file might differ
tail -20 /var/log/php7.0-fpm.log # Exact path/file might differ
Yep correct
i attached the error log from nginx that has sqlite3 error in it, the php7.0-fpm log without any errors and the lighttpd has no logs
error_nginx.txt (15,8 KB) php7.0-fpm.txt (2,0 KB)
Ah yes sorry of course I meant the Nginx log. Since an expected SQLite3 constant as well as a class is missing, I am pretty sure that the PHP SQLite3 module is not installed or not enabled for the used PHP instance. Please try:
apt install php7.0-sqlite3
phpenmod sqlite3
systemctl restart php7.0-fpm
systemctl restart nginxI have same Problem with Apache2 installing of php7.x-sqlite helps but I can not add new gravity list
For now I installed lighttpd and I set on other port (8080)
With lighttpd there is no Problems
i had the same issue.
in addition of sqlite and intl, i had to install php7.0-cgi php7.0-xml.
Globally with this new version, you have to install - check if you have installed the following:
sudo apt install cron curl dnsutils iputils-ping lsof netcat psmisc sudo unzip wget idn2 sqlite3 libcap2-bin dns-root-data libcap2 lighttpd php7.0-common php7.0-cgi php7.0-sqlite3 php7.0-xml php-intl
1 Like
Did you try add new Adlist in Group Management ?
I'm using php 7.3
yup, that working for me. (on raspberry pi (octopi))
I can add a new group, a new adlists and also assign this list to new group.
.
I've also tried before to repair my "pihole -r"
Nope i tried it but nothing help 
It must also be the way around, www-data must also be in group pihole.
nanopi@nanopi:~$ groups pihole
pihole : pihole www-data
Did you run
usermod -aG pihole www-data
and restated your server?
Yep i did it already
Hi.
Is there a final helpful solution now around?
I have the same problem after upgrade.
But I reverted back to an old vm snapshot.
Thanks
seems not, doesnt work for me any of these tricks.
None of this worked for me either... 
This worked for me running NGINX as well 