Hello Charul,
I apologize that you are receiving a reply only now. We are receiving an unusually high number or requests in our forums and we are trying to answer all of them as soon as we can.
I’m sorry about your QR scanning issue. I understand that your event is over by now, nonetheless I would love to help you find the source of the issue and get it fixed so this doesn’t happen in the future.
As a first I’d like to ask you to update Calendar plugins to the latest version and check if you are still experiencing the issue.
Also, if you can, try a different qr code scanner app. (What phone and app are you using?)
Looking forward to helping you fix this.
Cheers,
Andras