Permissions issues So, you're installing Drupal and have one of these installer errors:

The directory files is not writable. To proceed with the installation, please ensure that the files directory exists and is writable by the installer. If you are unsure how to create this directory and modify its permissions, please consult the on-line handbook or INSTALL.txt.
The Drupal installer requires write permissions to ./sites/default during the installation process. If you are unsure how to grant file permissions, please consult the on-line handbook.

To solve these errors, you neeed to modify the permissions on either the files directory or the sites/default directory (depending on the error message) so that it can be writable by the Drupal installer/web server process. Granting write permissions on Linux/Unix/Mac servers Granting write permissions on Windows servers