Error: This app cannot be enabled because it makes the server unstable✖

[toczekmj]

Steps to reproduce

1. Search app in Nextcloud's applications
2. Click enable
3. Popup with the following messages pops up: Error: This app cannot be enabled because it makes the server unstable✖
   

Expected behaviour

App should be enabled

Actual behaviour

Error occurs

Server configuration

Operating system:
Operating System: Ubuntu 22.04 Linux 6.8.4-2-pve x86_64
CPU: Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (8 cores)
Memory: 15.50 GB
Nextcloud running in docker instance, and so is MariaDB instance

Web server:
not sure

Database:
MariaDB 10.11.6

PHP version:
8.3.6

Version: (see admin page)
Nextcloud Hub 8 (29.0.0)

Updated from an older version or fresh install:
Fresh install

List of activated apps:
Activity
Calendar
Collaborative tags
Comments
Contacts
Contacts Interaction
Dashboard
Deleted files
Federation
File reminders
File sharing
Files download limit
First run wizard
Log Reader
Mail
Monitoring
Nextcoud Announcements
Nextcloud Office
Notes
Notifications
Password policy
PDF viewer
Photos
Privacy
Recommendations
Related Resources
Share by mail
Support
Talk
Teams
Text
Update notification
Usage survey
User status
Versions
Weather status

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your server installation folder

The content of config/config.php:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

or

Insert your config.php content here
Make sure to remove all sensitive content such as passwords. (e.g. database password, passwordsalt, secret, smtp password, 
…)


<?php
$CONFIG = array (
  'datadirectory' => '/data',
  'instanceid' => '************',
  'passwordsalt' => '*************',
  'secret' => '************',
  'trusted_domains' =>
  array (
    0 => '192.168.0.186:444',
    1 => 'drive.********.com',
    2 => 'drive.********.duckdns.org',
  ),
  'dbtype' => 'mysql',
  'version' => '29.0.0.19',
  'overwrite.cli.url' => 'https://192.168.0.186:444',
  'dbname' => 'nextcloud',
  'dbhost' => '192.168.0.186:3306',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'nextcloud',
  'dbpassword' => '*****************',
  'installed' => true,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'filelocking.enabled' => true,
  'memcache.locking' => '\\OC\\Memcache\\APCu',
  'upgrade.disable-web' => true,
);

Client configuration

Browser:
Brave

Operating system:
MacOS Ventura

Logs

Web server error log

[migrations] started
[migrations] 01-nginx-site-confs-default: skipped
[migrations] 02-default-location: skipped
[migrations] done
usermod: no changes
───────────────────────────────────────
      ██╗     ███████╗██╗ ██████╗
      ██║     ██╔════╝██║██╔═══██╗
      ██║     ███████╗██║██║   ██║
      ██║     ╚════██║██║██║   ██║
      ███████╗███████║██║╚██████╔╝
      ╚══════╝╚══════╝╚═╝ ╚═════╝
   Brought to you by linuxserver.io
───────────────────────────────────────
To support LSIO projects visit:
https://www.linuxserver.io/donate/
───────────────────────────────────────
GID/UID
───────────────────────────────────────
User UID:    1000
User GID:    1000
───────────────────────────────────────
using keys found in /config/keys
System config value memcache.local set to string \OC\Memcache\APCu
System config value filelocking.enabled set to boolean true
System config value memcache.locking set to string \OC\Memcache\APCu
System config value upgrade.disable-web set to boolean true
Removing richdocumentscode
[custom-init] No custom files found, skipping...
[ls.io-init] done.

Server log (data/nextcloud.log)

https://pastebin.com/raw/cFLDYSBq

Browser log

Insert your browser log here, this could for example include:

a) The javascript console log
nothing to see there 
b) The network log
https://drive.google.com/file/d/152NL3nsoJA26PQL9VX_YMx6SMWtov1KX/view?usp=sharing

[toczekmj]

In case someone is facing the same problem, seems that I've just found a solution.
In my case it was simple setup:

• Docker on server1:

  • NextCloud
  • MariaDB

• Docker on server2:

  • NGINX Reverse Proxy Manager with two addresses bound to NextCloud:
    • addres1.com which is my cloudflare proxied domain
    • and address2.duckdns.org which is bound to my local IP (192.168.0.XXX)

Even tho the NGINX proxy seemd to be configured properly for both cloudflare, and duckdns, the issue only exists on the address2.duckdns (which i have been using all the time while testing, since it is the one configured to work from the inside of my network). So to conclude, the solution was to simply access nextcloud apps and install TOTP using the public domain, and after that TOTP works like a charm, even when accessing nextcloud from local domain.