Upgraded my Wordpress site to PHP v8.4, critical error

[esc4p3]

Hi there. I should point out at the start, I am a very inexperienced website creator! I use GoDaddy as my web host and if I don't manually update my PHP version every now and then, they charge me an "extended support" cost. I updated to PHP v8.4 from v8.1 and it caused a critical error on the site, which according to the automated email I received, was due to the WPFTS plug-in.

Is WPFTS compatible with v8.4?

The full error message that came through on the email was this (which means nothing to me!)

<start of code>

Error Details

An error of type E_ERROR was caused in line 30 of the file /home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/extensions/includes/extractors/textmillio.php. Error message: Uncaught Error: Call to undefined function mb_strtolower() in /home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/extensions/includes/extractors/textmillio.php:30
Stack trace:
#0 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(341): {closure:/home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/extensions/includes/extractors/textmillio.php:3}()
#1 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters()
#2 /home/c5rbjwu6e108/public_html/wp-includes/plugin.php(522): WP_Hook->do_action()
#3 /home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/extensions/includes/wpfts_addon_file_search.class.php(22): do_action()
#4 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(341): WPFTS_Addon_File_Search->{closure:WPFTS_Addon_File_Search::__construct():12}()
#5 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters()
#6 /home/c5rbjwu6e108/public_html/wp-includes/plugin.php(522): WP_Hook->do_action()
#7 /home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/fulltext-search.php(239): do_action()
#8 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(341): {closure:/home/c5rbjwu6e108/public_html/wp-content/plugins/fulltext-search-pro/fulltext-search.php:154}()
#9 /home/c5rbjwu6e108/public_html/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters()
#10 /home/c5rbjwu6e108/public_html/wp-includes/plugin.php(522): WP_Hook->do_action()
#11 /home/c5rbjwu6e108/public_html/wp-settings.php(742): do_action()
#12 /home/c5rbjwu6e108/public_html/wp-config.php(101): require_once('/home/c5rbjwu6e...')
#13 /home/c5rbjwu6e108/public_html/wp-load.php(50): require_once('/home/c5rbjwu6e...')
#14 /home/c5rbjwu6e108/public_html/wp-admin/admin.php(35): require_once('/home/c5rbjwu6e...')
#15 /home/c5rbjwu6e108/public_html/wp-admin/index.php(10): require_once('/home/c5rbjwu6e...')
#16 {main}
thrown

<end of code>

Does this mean anything to anyone? Any help greatly appreciated....I've 'downgraded' the PHP back to version 8.1 and the site works fine:

WordPress version 6.9
Active theme: Vantage (version 1.20.32)
Current plugin: WP Fast Total Search Pro (version 3.78.258)
PHP version 8.4.15

[EpsilonAdmin]

Hi @esc4p3

While upgrading to PHP 8.4, you are also updating a set of PHP flags. Please check your PHP 8.4 configuration to ensure the multibyte string (mbstring) extension is enabled. If it’s disabled, please enable it.

This should fix the issue you described above. Let me know if the problem persists after applying this change.

Thank you!

[esc4p3]

@EpsilonAdmin hi there again. Fabulous!

Although I'm not exactly sure what enabling the extension actually does, luckily enough, I know enough to find and enable the extension within my cPanel interface.

I note that using PHP 8.1, the mbstring extension is enabled, but for some reason only known to GoDaddy, when version 8.4 is used, it de-selects mbstring (along with mysqli) making the website non-functional.

However, with your advice, the site is now back up and running. Thank you for the speedy and spot-on advice, very much appreciated.

[EpsilonAdmin]

Thank you again @esc4p3 for this bugreport and checked solution!