Go to your plugin editor, bring up user-avatar/user-avatar.php, and change line 100 from:
mkdir(WP_CONTENT_DIR.”/uploads/avatars/”, 0777, true);
to:
mkdir(WP_CONTENT_DIR.”/uploads/avatars/”, 0777);
Probably has something to do with the OS or version of PHP running, but this worked fine for me.
