[Closed] PHP Fatal error: Uncaught Error: Cannot assign an empty string to a string offset

Hello,

Thank you, I-ve been using your fresh WP install with all the right plugins and also a repeater structure used in original website.
In the fresh WP install the ACFML Sync. checkbox works fine and when post update button is clicked, no critical error occurs.

So, here is what I did in the original site where the critical problem still appears.
* I've disactivated all the plugins to have the same plugins and version than in the fresh WP install.
* I've selected a default template (Twenty twenty-four) and the critical error is still there.

I went into the error log and checked where in the code this error happens:

"PHP Fatal error: Uncaught Error: Cannot assign an empty string to a string offset in /nas/content/live/tigercatco1dev/wp-content/plugins/acfml/classes/strategy/repeater-sync/CheckboxHooks.php:46#012Stack trace:#012#0"

Within your fresh install I've inserted a debug code starting line 42 in file CheckboxHooks.php and function storeSynchroniseOption:

$synchroniseOption = CheckboxOption::get();

// PRINT LOG ---------------------------
$file = dirname(__FILE__).'https://cdn.wpml.org/log_synch.txt';
$log = '$trid / $synchroniseOption 1: '.$trid.' *** '.print_r($synchroniseOption,true)."\n\r";
file_put_contents($file, $log, FILE_APPEND);
// PRINT LOG --------------------------- */

------------------------------- Here is the result in the fresh WP install:
* Checkbox ACFML Sync unselected in the post
$trid / $synchroniseOption: 18 *** Array
(
[18] =>
)

* Checkbox ACFML Sync unselected in the post
$trid / $synchroniseOption: 18 *** Array
(
[18] => 1
)

------------------------------- Here is the result in original WP install:
* To unselect Checkbox ACFML Sync and update post triggers critical error!!!
There's no array as a result of "$synchroniseOption = CheckboxOption::get();"
And it seems not empty either???

$trid / $synchroniseOption: 173887 ***

What is strange is that if I forced ONCE to created an array to make sure it exist prior to trigger a critical error:
$synchroniseOption[$trid] = '';

Then all post works fine even after removing this forced array creation!!!
Just like if something was missing to create it in the first place.

------------------------------ Here is the full error JSON:
{
"installName": "tigercatco1dev",
"environment": "DEV",
"type": "error",
"date": "2023-12-10T12:52:45.877Z",
"severity": null,
"client": null,
"message": "PHP Fatal error: Uncaught Error: Cannot assign an empty string to a string offset in /nas/content/live/tigercatco1dev/wp-content/plugins/acfml/classes/strategy/repeater-sync/CheckboxHooks.php:46#012Stack trace:#012#0 /nas/content/live/tigercatco1dev/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/functions.php(17): ACFML\\Repeater\\Sync\\CheckboxHooks->storeSynchroniseOption(50304)#012#1 /nas/content/live/tigercatco1dev/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Either.php(207): WPML\\FP\\{closure}(Array)#012#2 /nas/content/live/tigercatco1dev/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Either.php(257): WPML\\FP\\Right->map(Object(Closure))#012#3 /nas/content/live/tigercatco1dev/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Promise.php(24): WPML\\FP\\Right->chain(Object(Closure))#012#4 /nas/content/live/tigercatco1dev/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/wp/classes/Hooks.php(50): WPML\\FP\\Promise->resolve(Object(WPML\\FP\\Right))#012#5 /nas/content/live/tigercatco1dev/wp-includes/class-wp-hook.php(324): WPML\\LIB\\WP\\Hooks::WPML\\LIB\\WP\\{closure}(50304)#012#6 /nas/content/live/tigercatco1dev/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)#012#7 /nas/content/live/tigercatco1dev/wp-includes/plugin.php(517): WP_Hook->do_action(Array)#012#8 /nas/content/live/tigercatco1dev/wp-content/plugins/advanced-custom-fields-pro/includes/acf-form-functions.php(143): do_action('acf/save_post', 50304)#012#9 /nas/content/live/tigercatco1dev/wp-content/plugins/advanced-custom-fields-pro/includes/forms/form-post.php(328): acf_save_post(50304)#012#10 /nas/content/live/tigercatco1dev/wp-includes/class-wp-hook.php(326): ACF_Form_Post->save_post(50304, Object(WP_Post))#012#11 /nas/content/live/tigercatco1dev/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)#012#12 /nas/content/live/tigercatco1dev/wp-includes/plugin.php(517): WP_Hook->do_action(Array)#012#13 /nas/content/live/tigercatco1dev/wp-includes/post.php(4760): do_action('save_post', 50304, Object(WP_Post), true)#012#14 /nas/content/live/tigercatco1dev/wp-includes/post.php(4862): wp_insert_post(Array, false, true)#012#15 /nas/content/live/tigercatco1dev/wp-admin/includes/post.php(453): wp_update_post(Array)#012#16 /nas/content/live/tigercatco1dev/wp-admin/post.php(227): edit_post()#012#17 {main}#012 thrown in /nas/content/live/tigercatco1dev/wp-content/plugins/acfml/classes/strategy/repeater-sync/CheckboxHooks.php on line 46",
"uuid": "b2ad3158-6f32-4ba2-8352-1b9c58358dc3"
}

------------------------------------------------------------

I do not know if it helps but that's were I am.

Thank you for your help.

JM