Fatal error: Uncaught Error: Class "Symfony\Component\String\AbstractString" not found in C:\www\Apache24\htdocs\agenda-dif\vendor\symfony\string\AbstractUnicodeString.php:29 Stack trace: #0 {main} thrown in C:\www\Apache24\htdocs\agenda-dif\vendor\symfony\string\AbstractUnicodeString.php on line 29