I recently moved my wordpress blog from a shared hosting to linode VPS. Migration was smooth except few tiny problems. One of them is doing updates to wordpress, plugins or themes.
I started getting this error:
To perform the requested action, WordPress needs to access your web server. Please enter your FTP credentials to proceed
To solve this problem first I had to configure an ftp server. Refer to this for more details:
Installing FTP Server in Ubuntu 12.04
Then I added the following to wp-config.php file
define('FTP_USER', 'user');
define('FTP_PASS', 'user-password');
define('FTP_HOST', 'localhost');
And it started working fine. No need restart the nginx or any other processes.