Neue Contao-Version, neuer Installationsfehler.

composer läuft samt Cache aufwärmen läuft durch, aber contao/install führt zur 500er-Seite.
Im Debug-Modus erhalte ich folgendes:

Argument 3 passed to Symfony\Component\EventDispatcher\Debug\TraceableE ventDispatcher::addListener() must be of the type int, float given, called in C:\Users\Public\Projekte\digeniotheme413-0\var\cache\dev\ContainerCVxJdKY\Contao_ManagerBun dle_HttpKernel_ContaoKernelDevDebugContainer.php on line 1617

in C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\event-dispatcher\Debug\TraceableEventDispatcher.php (line 58)
Code:
        }
        /**
         * {@inheritdoc}
         */
        public function addListener(string $eventName, $listener, int $priority = 0)
        {
            $this->dispatcher->addListener($eventName, $listener, $priority);
        }
        /**

Code:
TypeError:
Argument 3 passed to Symfony\Component\EventDispatcher\Debug\TraceableEventDispatcher::addListener() must be of the type int, float given, called in C:\Users\Public\Projekte\digeniotheme413-0\var\cache\dev\ContainerCVxJdKY\Contao_ManagerBundle_HttpKernel_ContaoKernelDevDebugContainer.php on line 1617

  at C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\event-dispatcher\Debug\TraceableEventDispatcher.php:58
  at Symfony\Component\EventDispatcher\Debug\TraceableEventDispatcher->addListener('security.authentication.success', array(object(Closure), 'onLogin'), 9223372036854775808.0)
     (C:\Users\Public\Projekte\digeniotheme413-0\var\cache\dev\ContainerCVxJdKY\Contao_ManagerBundle_HttpKernel_ContaoKernelDevDebugContainer.php:1617)
  at ContainerCVxJdKY\Contao_ManagerBundle_HttpKernel_ContaoKernelDevDebugContainer->getEventDispatcherService()
     (C:\Users\Public\Projekte\digeniotheme413-0\var\cache\dev\ContainerCVxJdKY\Contao_ManagerBundle_HttpKernel_ContaoKernelDevDebugContainer.php:1768)
  at ContainerCVxJdKY\Contao_ManagerBundle_HttpKernel_ContaoKernelDevDebugContainer->getHttpKernelService()
     (C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\dependency-injection\Container.php:239)
  at Symfony\Component\DependencyInjection\Container->make('http_kernel', 1)
     (C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\dependency-injection\Container.php:219)
  at Symfony\Component\DependencyInjection\Container->get('http_kernel')
     (C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\http-kernel\Kernel.php:215)
  at Symfony\Component\HttpKernel\Kernel->getHttpKernel()
     (C:\Users\Public\Projekte\digeniotheme413-0\vendor\symfony\http-kernel\Kernel.php:202)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (C:\Users\Public\Projekte\digeniotheme413-0\public\index.php:44)
Der Tatort ist meine Entwicklungsumgebung MAMP mit einem 32-Bit, PHP 7.4.
Hat jemand eine Idee, wie es zu dem Fehler kommt?