I had a Drupal 8 project installed from Drupal 8 sources what had been downloaded from Drupal 8 site. Recently I heard a good thought that it would be more comfortable to have the project originally installed via Composer. I did the migration and now the project has a structure likewise installed via Composer. That is, it has the "web" subdirectory with Drupal 8 files, the "vendor" directory isn't included in Drupal files and so on.
The site worked successfully after migration.
However, I ran into a problem. Namely, after migration, I couldn't use Drush on the project. The following error appeared upon trying to execute
Command cache-rebuild needs a higher bootstrap level to run - you will need to invoke drush from a more functional Drupal environment to run this command.
Command cache-rebuild requires Drupal core version 8+ to run.
My colleagues advised me to install Drush-launcher from GitHub as a shell for original Drush. I did it, this problem seemingly disappeared. But I ran into a next one. Namely, Now I can't use Drush for projects made on Drupal 7.
Is it possible to set up Drush for sites installed via Composer and without using the launcher?