I am using the latest version of Matomo On-Promise 4.15.1 and during installation I have this error message: “Unable to connect to database server: SQLSTATE[HY000]  Connection denied? e” After searching the internet, I would have to modify the config/config.ini.php file, but apparently this file is not created during the installation. I install, uninstall and reinstall several times via ftp Filezila and I am still faced with the same message. Of course I created a database at my web host, the version of PHP used is 8.1. In short I do not know what to do to solve this problem and solve it becomes urgent because my site is online and not yet compliant with the GDPR because of this problem
I guess this is due to the permission on your web server.
If you use a Linux based server (Ubuntu, Debian, CentOS…) you have to configure proper right in order to let Apache (or Nginx) manager your installation folder.
If you don’t configure the rights, Matomo can have issues on installation and plugin update + caching files.