Hello Aspirant,

It's generally not possible to not to upload class 12 CBSE Marksheet because few documents are must and has to be given while applying for JEE Advanced application form their might be some error or miss-understanding.

You better recheck and rectify the problem in the existing admission form or cancel the previous one and apply for new one.

Better way to fill the form consciously with proper details with taking your time, it's the vital step for your carrier.

Hope you have understood what you have been guided to, and it will help you out.

Best of Luck.