php sdk 3 date upsert

php sdk 3 date upsert

hello,
i am trying to upsert a date via php sdk 3 and i always get this error

I tried both string "aaaa-mm-dd" and a datetime object :
$date = "2020-01-01";  // this gets "PHP exception":{"message":"","file":"/var/www/vendor/zohocrm/php-sdk/src/com/zoho/crm/api/util/Converter.php"
OR $date =  new DateTime("2020-01-01"); //this trigger a 202 response code

below is my code:
$field = new Field("Date_de_cr_ation_LPDV");
$record1->addFieldValue($field, $value);
etc...