autotutorial

$arr['notexist'];
// inizialize empty array
$arr = array();
// array with any value
$arr['notexist'] = 1;

From php 7 the errors are transformed into exceptions, the use of the @ error control operator hides the error by temporarily lowering error_reporting to 0.

perform until the third steep https://wordpress.org/support/topic/no-results-in-media-search/#post-12043004 without
$show_errors = true;
Curls on other domains? Does it also work for https? (the last message indicates the expiration of the certificate …. https in use)
Create test.php

<?php
Undefined_constant;
$var_error[] = (int) error_get_last();
function ABC() {
set_error_handler('var_dump',0);
return;
}
ABC();
$var_error[] = (int) error_get_last();
print_r($var_error);

//Your code curl with HTTPS and curl erno here

WordPress 5.2 have WSOD protection only if error_get_last() work.

I asked for more information to understand how you were working ..
no you don’t have to change the values but I have to understand how you work.
Make sure you backup your files and database 1) https://wordpress.org/support/article/wordpress-backups/

2) Enable log_errors = on in your php.ini

3) in the wp-config.php file if this is not enable

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
// From WordPress => 5.1 you set the directory log, change with new locations
// Ex. define( 'WP_DEBUG_LOG', '/tmp/wp-errors.log' );
// Enable show error database
$show_errors = true;

More information here https://wordpress.org/support/article/debugging-in-wordpress/

4) Confirm that you are not editing the uploads folder with this constant via wp-config.php / plugin or your theme? https://wordpress.org/support/article/editing-wp-config-php/#moving-uploads-folder

5) What encoding are you using in the database and in your php?

6) Returning to your problem again, WordPress only treats strings without special characters because it is difficult to manage them
On some hosts special characters give problems * 1 (folder or filename) * 2 search by filename is of natural conventions naming file * 3 Json (api rest only requires valid UTF-8 data).

Ex. for file name Auswahl einschränken.jpg
Search Media library in gred view
(without errors … Notice, Warnings PHP etc.)
Auswahl einschränken
https://domain.com/wp-admin/upload.php?search=Auswahl+einschr%C3%A4nken
Percent Enconding , query string https://en.m.wikipedia.org/wiki/Percent-encoding

Theoretically this is the right way to search for the file even if I have to understand the functions and objects involved in WordPress.
Where can I find the documentation for the filter_action filter?

Can you check version.php and specify the wordpress release version and the minimum php version?
I suppose you are not currently using the latest version of wordpress so you have to set php to a minimum …
By Default wordpress from 3.0 creates an uploads folder, why do you use img?

You have this code on your wp-includes/default-constants.php ? https://github.com/WordPress/WordPress/blob/master/wp-includes/default-constants.php#L311

probably ini_set is disabled for security you can modify wp-includes / load.php at your own risk as follows … you only get the error page.

Before https://github.com/WordPress/WordPress/blob/master/wp-includes/load.php#L309

if(!isset($PHP_SELF)) {
$PHP_SELF = '';
}

After
global $PHP_SELF;

After https://github.com/WordPress/WordPress/blob/master/wp-includes/load.php#L345

if(!(strtolower((string) @ini_get('log_errors')) == 'on' || (string) @ini_get('log_errors') == '1' )) {
if (!function_exists('wp_fix_server_vars')) {
require_once ABSPATH . WPINC .'/load.php';
}
wp_fix_server_vars();
error_log("you have a error here $PHP_SELF\n",3,$log_path);
}

the link that I left you clocks there are two plugins for the multimedia library and since I don’t see you convinced before any modification you make backups of the ftp files and the mysql database in case of error you can return to the starting point.