Wordpress asks for FTP credentials to upgrade

It asks ftp credentials because wordpress probably does not have write permission on your wordpress root folder.So, it tries to put wp upgrade via FTP. In order to fix that go to your root folder of wordpress site and run;

sudo chown -R www-data:www-data wordpress

Try adding this line at the end of your wp-config.php file:

define('FS_METHOD','direct');

It sets the direct method and update without asking for FTP credentials.

Wordpress asks for your FTP credentials when it doesn't have write access to all the folders it needs. It's a misleading error message - it should really just say "Please give me write permissions on your root folder while I do this upgrade".

This problem seems especially common in IIS users where the permissions/user accounts are a bit more arcane.

Essentially, to solve it:

• Give your Application Pool user (often IUSR for Windows users) write and modify privileges on the root folder of your wordpress installation.
• Run the automated upgrade from the Wordpress dashboard, which should happen nice and easily now.
• Remove the write/mod privileges from IUSR to resecure your installation (making sure it can still write to your plugins directory)