Fatal error: Uncaught Error: Interface 'Doctrine\Common\Collections\Collection' not found in C:\Apache24\htdocs\InvoiceTracking\vendor\doctrine\collections\lib\Doctrine\Common\Collections\ArrayCollection.php:41 Stack trace: #0 {main} thrown in C:\Apache24\htdocs\InvoiceTracking\vendor\doctrine\collections\lib\Doctrine\Common\Collections\ArrayCollection.php on line 41