You updated your Piwigo, and get Notice: Trying to access array offset on value of type null in main.inc.php on line 68 or similar errors?
Well, the fix is easy.
Just go to your piwigo installation, and change to the subdirectory includes. Edit the file config_default.inc.php. Around line 474 you will find
$conf['show_php_errors'] = E_ALL;
Change it to
$conf['show_php_errors'] = E_ERROR;
This is just another easy hack on your own Piwigo installation. As much as I like the efforts the developers put into Piwigo, in my opinion there is no way to use it without some knowledge of PHP and your server. Too many small glitches influence the use of this wonderful software. The latest issues appear because Piwigo seems to be not ready to use with PHP 7.4 – as example. Other issues are created due some „laziness“. It seems to me the guys forgot to check for null values, as the error Trying to access array offset on value of type null implies. In an ideal world such issues would not happen because the developers take care of it. This is no complaint towards the guys who maintain Piwigo.