When I started with PHP I had to implement an administration system for a small organization.
They using the smallest and most cheap web hosting to host the system and also their websites.
They host three systems and websites on three different web spaces.
Some weeks ago I got a call from them, that the system doesn't work. After a short investigation, I discovered that their '"designer"/boyfriend-of-the-boss created a new Wordpress site and thought it would be a good idea to change the PHP system to 7.2. The system runs on an old CakePHP (don't kill me for that, I had no experience -.-') version, which does't work with PHP 7.2.
I told them what the issue was and that they shouldn't change the PHP version to 7.2 because the system won't run on this version.
Some a week later, the same call, another administration system, the same reason, the same warning from my site.
Today, the third system doesn't work. I told them this is probably the PHP 7.2 problem again and explained, how they could resolve it themselves.
Suddenly I got an email from the designer: no, this time it is another problem, he didn't change anything and it just doesn't work anymore. And it is very urgent.
Guess what was the problem...AGAIN!