Cannot access web ui

Please follow the below template, it will help us to help you!

Expected Behaviour:

Can access the web admin panel on IP/admin or hostname/admin

Software:

$lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description:    Raspbian GNU/Linux 10 (buster)
Release:        10
Codename:       buster

$uname -a
Linux home 5.10.103-v7l+ #1529 SMP Tue Mar 8 12:24:00 GMT 2022 armv7l GNU/Linux

$pihole -v
Pi-hole version is v5.10 (Latest: v5.10)
AdminLTE version is v5.12 (Latest: v5.12)
FTL version is v5.15 (Latest: v5.15)

Hardware:

Raspberry Pi 4 with 4GB of RAM

Actual Behaviour:

An install of pihole from 2019, worked fine but recently accessing ip/admin Cannot GET /admin/
Did pihole updatePihole
Did sudo apt update && sudo apt upgrade
Tried pihole -r and the repair option(not reconfigure), and it reported no errors.
Everything works except the web UI.
Also looked through many issues and none seemed to fix my problem.

Debug Token:

https://tricorder.pi-hole.net/lwAANTKA/

The debug log was able to connect to the web interface.

You seem to have some issue with lighttpd bouncing very frequently:

   2022-05-13 23:27:02: (server.c.958) [note] graceful shutdown started 
   2022-05-13 23:27:02: (server.c.2059) server stopped by UID = 0 PID = 15515 
   2022-05-13 23:27:02: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-13 23:27:02: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-13 23:27:21: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-13 23:27:21: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-13 23:27:21: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-13 23:57:29: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-13 23:57:40: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-13 23:57:40: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-14 00:33:35: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-14 00:33:36: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-14 00:33:36: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-14 00:38:05: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-14 00:38:14: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-14 00:38:14: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-14 00:43:02: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-14 00:43:03: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-14 00:43:03: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-14 00:48:19: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-14 00:48:20: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-14 00:48:20: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 
   2022-05-14 00:52:09: (server.c.2059) server stopped by UID = 0 PID = 1 
   2022-05-14 00:52:09: (server.c.1464) server started (lighttpd/1.4.53) 
   2022-05-14 00:52:09: (server.c.1493) WARNING: unknown config-key: alias.url (ignored) 

You are on the latest versions of each module.

What is the exact URL you are trying to access the admin page with?

either http://home.local/admin or http://192.168.0.2/admin

Thanks, those are the proper URLs to use.

The logs from lighttpd posted above show that the server is being stopped by the OSes init system.

Can you please run:

sudo systemctl status --full --no-pager lighttpd.service

And check sudo journalctl -u lighttpd to see if there are any errors or indications on why the init system is killing the process.

$sudo systemctl status --full --no-pager lighttpd.service
● lighttpd.service - Lighttpd Daemon
   Loaded: loaded (/lib/systemd/system/lighttpd.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2022-05-14 00:52:09 CEST; 21h ago
 Main PID: 5171 (lighttpd)
    Tasks: 6 (limit: 4915)
   CGroup: /system.slice/lighttpd.service
           ├─5171 /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
           ├─5178 /usr/bin/php-cgi
           ├─5179 /usr/bin/php-cgi
           ├─5180 /usr/bin/php-cgi
           ├─5181 /usr/bin/php-cgi
           └─5182 /usr/bin/php-cgi

May 14 00:52:09 home systemd[1]: Starting Lighttpd Daemon...
May 14 00:52:09 home lighttpd[5164]: 2022-05-14 00:52:09: (server.c.1493) WARNING: unknown config-key: alias.url (ignored)
May 14 00:52:09 home systemd[1]: Started Lighttpd Daemon.

$sudo journalctl -u lighttpd
-- Logs begin at Sat 2022-05-14 00:38:07 CEST, end at Sat 2022-05-14 22:14:31 CEST. --
May 14 00:38:12 home systemd[1]: Starting Lighttpd Daemon...
May 14 00:38:14 home lighttpd[539]: 2022-05-14 00:38:12: (server.c.1493) WARNING: unknown config-key: alias.url (ignored)
May 14 00:38:14 home systemd[1]: Started Lighttpd Daemon.
May 14 00:43:03 home systemd[1]: Stopping Lighttpd Daemon...
May 14 00:43:03 home systemd[1]: lighttpd.service: Succeeded.
May 14 00:43:03 home systemd[1]: Stopped Lighttpd Daemon.
May 14 00:43:03 home systemd[1]: Starting Lighttpd Daemon...
May 14 00:43:03 home lighttpd[1914]: 2022-05-14 00:43:03: (server.c.1493) WARNING: unknown config-key: alias.url (ignored)
May 14 00:43:03 home systemd[1]: Started Lighttpd Daemon.
May 14 00:48:20 home systemd[1]: Stopping Lighttpd Daemon...
May 14 00:48:20 home systemd[1]: lighttpd.service: Succeeded.
May 14 00:48:20 home systemd[1]: Stopped Lighttpd Daemon.
May 14 00:48:20 home systemd[1]: Starting Lighttpd Daemon...
May 14 00:48:20 home lighttpd[3770]: 2022-05-14 00:48:20: (server.c.1493) WARNING: unknown config-key: alias.url (ignored)
May 14 00:48:20 home systemd[1]: Started Lighttpd Daemon.
May 14 00:52:09 home systemd[1]: Stopping Lighttpd Daemon...
May 14 00:52:09 home systemd[1]: lighttpd.service: Succeeded.
May 14 00:52:09 home systemd[1]: Stopped Lighttpd Daemon.
May 14 00:52:09 home systemd[1]: Starting Lighttpd Daemon...
May 14 00:52:09 home lighttpd[5164]: 2022-05-14 00:52:09: (server.c.1493) WARNING: unknown config-key: alias.url (ignored)
May 14 00:52:09 home systemd[1]: Started Lighttpd Daemon.

dmesg -T | grep -i 'oom\|voltage'

dmesg -Tl emerg,alert,crit,err

?