When,I am going to login on magento connect with valid credentials. it through an error “Invalid login credentials”.

Please go to Root folder of your Magento project.
and than edit this file..
/downloader/connect.cfg

In this file lookup 
ftp://[username]:[pass]@[host]/[path-to-webfolder]/”;s:9:”sync_pear”;b:0;}

Check if [username], [pass] and [host] and [path-to-webfolder] 
corresponds to what it should be to logon via ftp to your server.

by