Hello,
After a member adds a vehicle and the admin approves it, the following error occurs.

TypeError: IPS\DateTime::ts(): Argument #1 ($timestamp) must be of type int, null given, called in /var/www/vhosts/agirmekan.com/httpdocs/system/Content/Item.php on line 7485 (0)

#0 /var/www/vhosts/agirmekan.com/httpdocs/system/Content/Item.php(7485): IPS\DateTime::ts()

#1 /var/www/vhosts/agirmekan.com/httpdocs/system/Content/Content.php(680): IPS\Content\Item->apiOutput()

#2 /var/www/vhosts/agirmekan.com/httpdocs/system/Content/Controller.php(1126): IPS\Content->modAction()

#3 /var/www/vhosts/agirmekan.com/httpdocs/system/Dispatcher/Controller.php(128): IPS\Content\Controller->moderate()

#4 /var/www/vhosts/agirmekan.com/httpdocs/system/Content/Controller.php(124): IPS\Dispatcher\Controller->execute()

#5 /var/www/vhosts/agirmekan.com/httpdocs/applications/garage/modules/front/garage/vehicle.php(72): IPS\Content\Controller->execute()

#6 /var/www/vhosts/agirmekan.com/httpdocs/system/Dispatcher/Dispatcher.php(169): IPS\garage\modules\front\garage\vehicle->execute()

#7 /var/www/vhosts/agirmekan.com/httpdocs/index.php(16): IPS\Dispatcher->run()

#8 {main}

These are internal Invision functions which are failing for you. The same as deleting. You will need to update to the latest release of contact Invision.