You are using the documentation for version 4.3.8. Go here for the latest version.
Version Notes for 3.1.0¶
With 3.1.0 we needed to make some changes to where and how avatars are stored. The updater will attempt to move all default avatars to a new directory, but there’s a slim chance you might see an error. Here’s how to deal with them.
Please correct the avatar path in your config file.
Double check your config file to ensure
avatar_path is set to a valid path. If you don’t have an
avatar_path in your config file, set one temporarily for the update:
$config['avatar_path'] = '/path/to/images/avatars';
Please correct the permissions on your avatar directory.
Ensure that the correct permissions are set on your avatar directory. It must be writable. See File Permissions for details.