Fatal error on 4.3 with < WP6.6

@antonynz thank you for the heads up – it’s a core function that we were expecting to be there, and now that you’ve pointed that out we’re issuing a patch asap. The next one will be 4.3.1 and should be out right after a quick QA. We will report back here for you when it’s complete.

@antonynz 4.3.1 should be ready – tested for that issue you brought up. Thanks so much for pointing that out.

I added this code under wp-includes/option.php file and it is SOLVED.

function wp_determine_option_autoload_value( $option, $value, $serialized_value, $autoload ) {
// Check if autoload is a boolean.
if ( is_bool( $autoload ) ) {
    return $autoload ? 'on' : 'off';
}

switch ( $autoload ) {
    case 'on':
    case 'yes':
        return 'on';
    case 'off':
    case 'no':
        return 'off';
}

/**
 * Allows to determine the default autoload value for an option where no explicit value is passed.
 *
 * @since 6.6.0
 *
 * @param bool|null $autoload The default autoload value to set. Returning true will be set as 'auto-on' in the
 *                            database, false will be set as 'auto-off', and null will be set as 'auto'.
 * @param string    $option   The passed option name.
 * @param mixed     $value    The passed option value to be saved.
 */
$autoload = apply_filters( 'wp_default_autoload_value', null, $option, $value, $serialized_value );
if ( is_bool( $autoload ) ) {
    return $autoload ? 'auto-on' : 'auto-off';
}

return 'auto'; }

@oneinamillion this function exists in wp 6.6, so if you update to that version you’ll have another fatal error trying to define the same function twice. We’ve patched the plugin to 4.3.1 yesterday that you should have been able to update and resolve that same problem the right way ??