Your requirements could not be resolved to an installable set of packages.
Problem 1
contao-community-alliance/merger2 4.2.0 requires ext-json ~1.2 -> it has the wrong version (8.0.7) installed. Install or enable PHP's json extension.
contao-community-alliance/merger2[4.2.1, ..., 4.2.2] require symfony/config ^3.0 || ^4.0 -> found symfony/config[v3.0.0, ..., v3.4.47, v4.0.0, ..., v4.4.25] but the package is fixed to v5.2.10 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
Die Installation bricht mit Fehlermeldung ab: