Creating ADM-Account - Page loads for half a second

Hello everyone,

currently, I am encountering an issue after the initial installation of Nextcloud (NC). The installation itself proceeds without any problems. After installing it on my Ubuntu system, I access the NC web interface and enter my information, including username, password, data directory, DB user, etc. When I click “Install” after entering the details, the page loads for 0.X seconds, and I find myself back on the same page, having to fill in all the information again. I have tested this with multiple browsers - Chrome, Opera, Edge - and all browsers yield the same result. I haven’t found any errors in the logs so far. All the provided data is correct. Even if I enter incorrect data, the same thing happens. Does anyone have any ideas or suggestions for me?

Information about my installation:

Provider: Local - Proxmox - Container - Ubuntu 22.04.3 LTS
Hardware: PC - Proxmox 8.1.3
Nextcloud Version: 28.0.1
PHP Version: PHP 8.2.14
Database: MariaDB Ver 15.1 Distrib 10.6.12-MariaDB
Apache version: 2.4.52
Is NC running in Docker, Snap, or VM: Container in Proxmox
Network breakdown: e.g., Router>Switch>PI>: Router - AP - Switch - PC - Proxmox/Bridge
Recent server updates: No
Have you checked the logs for Nextcloud and the system? Unfortunately, no revealing error stands out.
When did the error occur? Initial installation - Accessing the website, creating the administrative account, entering database details & data directory.

Found the mistake - in the php.ini there was an wrong entry for upload_max_filesize and post_max_size: