Permissions are a common problem when installing WP. It took me hours to try to figure out the best permissions configurations and finaly I realized that there is a filesystem method in WP-config that overrides the direct file I/O by using the FTP credentials:

In wp-config.php

Change

define(‘FS_METHOD’,’direct’);

to

define(‘FS_METHOD’,’ftpsockets’);

If the above does not solve your permission problems try:

$sudo chown -R YourUserName:www-data

$sudo chmod -R 775 *

Resources

• Changing File Permissions
• Editing wp-config.php
•  One-Click Plug-in Upgrades – Could not create directory