Installation C 4.13 - bricht mit Fehlercode 1 ab (contao:install-web-dir)

Hallo zusammen,
ich scheitere eben an einer Contao-Installation bei Mittwald. (Contao 4.13, PHP 8.1)

Die Installation bricht ab mit

Code:

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> Contao\ManagerBundle\Composer\ScriptHandler::initializeApplication
Script Contao\ManagerBundle\Composer\ScriptHandler::initializeApplication handling the post-install-cmd event terminated with an exception
In ScriptHandler.php line 97:
                                                                         
  An error occurred while executing the "contao:install-web-dir" command: 
                                                                         
install [--prefer-source] [--prefer-dist] [--prefer-install PREFER-INSTALL] [--dry-run] [--dev] [--no-suggest] [--no-dev] [--no-autoloader] [--no-progress] [--no-install] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--apcu-autoloader-prefix APCU-AUTOLOADER-PREFIX] [--ignore-platform-req IGNORE-PLATFORM-REQ] [--ignore-platform-reqs] [--] [<packages>...]
# Process terminated with exit code 1
# Result: General error

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Hat jemand eine Idee? Wo kann ich ansetzen?
Danke.