Using PHP-FPM (FastCGI Process Manager) to run web pages and web applications has many advantages, especially when compared to older techniques such as PHP running as an Apache module. One of the most important benefits is that PHP-FPM significantly improves performance and scalability by allowing finer-grained management and optimization of PHP processes. In this way, we can use the server's resources more efficiently, reduce the response time, and our system can remain stable even in the event of heavy traffic. However, over time, the PHP versions of our web applications may become outdated, which the various control panels do not update. In this description, we will see in a few steps how we can easily modify our manual settings so that our websites and web applications also work with the correct PHP version.

Another era has come again, when our Debian 10 (Buster) server has also run out of time, and it has become a burning task to do something about this problem. In this tutorial, we will upgrade a perfect Debian 10 (Buster) server to Debian 11 (Bullseye). On this page, we review the necessary tasks before the update, which we use to prepare our system for the new main version.

The operating system running on our Debian-based web servers will become obsolete over time, so over time it will be necessary to completely upgrade the distribution. In this description, we will perform a complete upgrade of a Debian 9 (Stretch) web server to Debian 10 (Buster). There are many features on the server that will also be updated. On the first page of this description, we will perform the pre-upgrade steps to prepare your system for a secure upgrade.

If there is a major change to your Debian system - so you don't just need to upgrade one or two sub-versions - you will get an error message during a smooth upgrade:
This must be accepted explicitly before updates for this repository can be applied. See apt-secure (8) manpage for details.
This troubleshooter will fix this.

When you are not using the latest version of a Linux distribution, oddities may arise. For example, in Debian 9, you may receive a "public key not available" (NO_PUBKEY) error message when updating the backports package. We will remedy this problem in this short troubleshooter.