Drupal 8 does not support PHP version 5. It requires a minimum PHP version of 7.0. Please see here for Drupal install requirements
Drupal Installation Requirements - Drupal.org
So you will have to upgrade PHP on your machine. Also PHP 5.0 is no longer supported and is not secure. So you might want to upgrade PHP on your server any way.
PHP Supported ...
"Drush was unable to query the database" tells you that your issue isn't a missing table, but a configuration issue.
You do need to start with an empty but working D8 site before you try running the migration. I'm thinking you didn't initialize your site after downloading the code with composer?
To be clearer: composer is a tool for managing code, not for ...
I had a similar issue on Windows 10. I didn't notice where the issue was coming from at first because I had Drush installed both globally and locally. After uninstalling drush globally, I noticed drush was not found anymore. After adding my local drush to my PATH I finally managed to launch the site install command.
In symfony I would delete vendor dir and run composer install. But in
drupal not all files are in vendor dir.
What is the best workflow in this case? Should I manually delete old
vendor files (what dirs exactly?)
See .gitignore in your project dir:
# Ignore directories generated by Composer
Normally you can simply update core and all extensions in a single pass:
Only if this doesn't work, try to update core in a separate step by following the procedures described in the drupal composer project:
composer update drupal/core webflo/drupal-core-require-dev "symfony/*" --with-dependencies
Solved it. I had to add that "webflo/drupal-core-require-dev" to update command to be updates as well, because without that core couldn't be updated:
composer update drupal/core "webflo/drupal-core-require-dev" --with-dependencies
Saw that in "known issues" section. :/
It's really strange - what's the purpose of --with-dependencies when I have to add ...