How to fix the «Can't create directory var/generation» issue?

[dmitry_fedyuk (Dmitrii Fediuk)]

It is a Magento 2.0 / 2.1 filesystem permissions issue.
You can fix it with the command:

chmod -R -v 777 var/generation

[dmitry_fedyuk (Dmitrii Fediuk)]

See also:

• Since 2016-12-28, the var/generation folder has been renamed to generated/code in Magento 2.2
• How to fix the «Can’t create directory ‘generated/code’ in Magento/Framework/Code/Generator.php» Magento 2.2 issue?
• How to fix the «cache_dir ‘var/cache’ is not writable» issue?