core-bundle/src/Resources/contao/library/Contao/Database/Updater.php
public function run292Update()
	{
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `startTime` `startTime` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `endTime` `endTime` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `startDate` `startDate` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `endDate` `endDate` int(10) unsigned NULL");
		$this->Database->query("UPDATE tl_calendar_events SET endDate=null WHERE endDate=0");
	}
public function run292Update()
	{
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `startTime` `startTime` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `endTime` `endTime` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `startDate` `startDate` int(10) unsigned NULL");
		$this->Database->query("ALTER TABLE `tl_calendar_events` CHANGE `endDate` `endDate` int(10) unsigned NULL");
		$this->Database->query("UPDATE tl_calendar_events SET endDate=null WHERE endDate=0");
	}
Version 2.9.2 update