Unable to update field in Sales Order Line via REST API

hi, i am trying to update a field on an order line via the PUT method on this endpoint, but the only response i get is “false”, no matter what body i post…
the error code in the backend is “-2”, but no further explanation.

has anyone been able to update fields in this way?

in the apache logs i see this:

AH01071: Got error 'PHP message: PHP Warning: Undefined property: stdClass::$desc in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 420PHP message: PHP Warning: Undefined property: stdClass::$label in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 421PHP message: PHP Warning: Undefined property: stdClass::$subprice in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 426PHP message: PHP Warning: Undefined property: stdClass::$qty in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 427PHP message: PHP Warning: Undefined property: stdClass::$remise_percent in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 428PHP message: PHP Warning: Undefined property: stdClass::$tva_tx in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 429PHP message: PHP Warning: Undefined property: stdClass::$localtax1_tx in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 430PHP message: PHP Warning: Undefined property: stdClass::$localtax2_tx in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 431PHP message: PHP Warning: Undefined property: stdClass::$price_base_type in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 432PHP message: PHP Warning: Undefined property: stdClass::$info_bits in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 433PHP message: PHP Warning: Undefined property: stdClass::$date_start in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 434PHP message: PHP Warning: Undefined property: stdClass::$date_end in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 435PHP message: PHP Warning: Undefined property: stdClass::$product_type in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 436PHP message: PHP Warning: Undefined property: stdClass::$fk_parent_line in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 437PHP message: PHP Warning: Undefined property: stdClass::$fk_fournprice in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 439PHP message: PHP Warning: Undefined property: stdClass::$pa_ht in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 440PHP message: PHP Warning: Undefined property: stdClass::$special_code in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 442PHP message: PHP Warning: Undefined property: stdClass::$array_options in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 443PHP message: PHP Warning: Undefined property: stdClass::$fk_unit in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 444PHP message: PHP Warning: Undefined property: stdClass::$multicurrency_subprice in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 445PHP message: PHP Warning: Undefined property: stdClass::$ref_ext in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 447PHP message: PHP Warning: Undefined property: stdClass::$rang in [-----HIDDEN-----]htdocs/commande/class/api_orders.class.php on line 448', referer: https://dev.erp.technoform-nw.ndrx.eu/api/index.php/explorer/

update, even after adding all of these fields in the body, still no luck. keep getting the same error message

Update: might be blocked by the status of the sales order.
when the sales order is in DRAFT, the update works.
so i will try to set the status to 0 via api, update the line and reset the status to 1

Final update:
the approach described above, worked.