Update only one property in infoblock?

Question

PHP

Tell me more, such a problem has appeared, that is, when updating the date, all the other properties are overwritten so as not to list all the properties in the array, there is still a method that can only update the date of the element

<?
include($_SERVER["DOCUMENT_ROOT"] . "/bitrix/modules/main/include/prolog_before.php");
define("NO_KEEP_STATISTIC", true);
define("NO_AGENT_STATISTIC", true);
if(CModule::IncludeModule("iblock")){ 
 
if (isset($_GET['ID']) && intval($_GET['ID'])):
    $newDate = ConvertTimeStamp(time(), "FULL");
    $elProps = array(
            "MODIFIED_BY"       => $USER->GetID(),       
            "IBLOCK_ID"         => 3,
            "ACTIVE_FROM"       => $newDate,
            "ACTIVE"            => "Y",
        );
    $newEl = new CIBlockElement;
      $res = $newEl->Update($_GET['ID'], $elProps);
    echo $newDate;
endif;
die();
}

Answer 1

You can use the CIBlockElement::SetPropertyValuesEx function to update an arbitrary number of properties. Example CIBlockElement::SetPropertyValuesEx($ID_ELEM, false, array($PROPERTY_CODE => Array ("VALUE" => $VALUE)));

Answer 2

Maybe the time format in $newDate is wrong. Try to manually set the date for the test, for example, 05/05/2016.
See if $res returns true or false?
At the end of the code, check the value of $newEl->LAST_ERROR?