composer prohibits

composer outdated drupal/*
composer show drupal/*

This manual works till version D8.6.11 (8.6.11 and higher require twig 1.38.2), so need at first update twig to this version with:

composer require 'twig/twig:1.38.2'

Composer prohibits - zobrazí závislosti, kvôli ktorým update zlyhá:

composer prohibits drupal/core:8.6.15

Composer update - update modulov podla composer.json