PHP deprecation warning in /wp-admin/includes/class-automatic-upgrader-skin.php

[nexbridge]

The following warnings are being triggered in the above file when the WordPress version auto-updates.

On line 87:

str_contains(): Passing null to parameter #1 ($haystack) of type string is deprecated

On line 93:

trim(): Passing null to parameter #1 ($string) of type string is deprecated

The PHP version is 8.2.

[sainathpoojary]

The issue occurred because $string was uninitialized when $feedback was neither an error nor a string, resulting in null being passed to str_contains() and trim(), which is deprecated in PHP 8.2. This fix ensures $string is always initialized as an empty string before use, preventing these warnings.

[nexbridge]

Thanks @sainathpoojary, but in PHP if a variable is not initialised then it would throw a different warning - the issue here seems to be that the variable is being set to NULL in some cases and this is then causing the deprecation warning when it's passed into str_contains() or trim(). The variable is being set on lines 76, 80 and 84, however judging by the code I doubt that lines 76 or 84 would return a NULL value, so it may be as simple as just adding a null coalescing operator on line 80:

<?php
$string = $feedback ?? '';

To that end I've added some debug lines to test my theory the next time it happens!

[sainathpoojary]

Thanks for the clarification! You’re right if the variable were truly uninitialized, we’d expect a different warning. It makes sense that $feedback might explicitly be null in some cases, leading to the deprecation warning when passed into str_contains() or trim(). I’ll test the fix with auto-updates, and if it works as expected, I’ll raise a PR. 🚀