Ever wondered why Magento connect Gives you this error when you try to install an extension?
First of all make sure /downloader folder has enough permissions..
Connect to you VPS via SSH
cd /home/magentodir
Perform CHMOD -R 777 downloader/ downloader/*
Now Retry the Magento extension if it still returns invalid header response open your PHP.ini
And verify that php CURL Extension hasn’t been disbled. (might be on multiple lines).
Once you have enabled PHP-Curl restart apache /etc/init.d/httpd restart (or if your using php-fpm) /etc/init.d/php-fpm restart
Now open Magento connect once again and verify that you can install the magento extension.
