`Doctrine\DBAL\Types\VarDateTimeImmutableType` not found

[VladimirCreator]

Error: Class "Doctrine\DBAL\Types\VarDateTimeImmutableType" not found in .../vendor/carbonphp/carbon-doctrine-types/src/Carbon/Doctrine/DateTimeImmutableType.php:8

what does it even mean?

[DerManoMann]

Looks like your classloader is not set up correctly - unlikely to be an issue with swagger-php itself. swagger-php requires classloading in order to be able to use reflection to inspect the PHP code it is scanning. A couple of issues around class loading are explained in the FAQ.