Hi Vaibhavi,

I think you are facing the issue because you are probably going to the older version of Login page (last year's login page by AICTE). Please try this link: https://ntacmat.nic.in/NTACmat/Root/Home.aspx

Use the application number generated along with the password you had set. I'm sure this will work out! Goodluck!

There might be technical glitches which prompts such errors. 

You can cintact CMAT official via email or helpline number stating your concern and they shall revert you with best possible solution  

Make sure you are using right passwords and login Id . Also check for typos and NumLock and Caps lock which can cause hindrnaces inlogging in.