The most recent request was denied because it had an invalid security token. Ple

Dear, I have setup Joomdonation successfully on my website but when I fill donation form and select any payment after that press donation submit button so I am getting following error

(the most recent request was denied because it contained an invalid security token. Please refresh the page and try again.)

Hi Raheel,
Please submit ticket and send your site url with super admin account. We will check the issue for you
Thanks
Dam

Thanks Dear, I have submitted ticket

Answered through ticket system
Thanks
Dam

I have this issue with only one person who tries to make a donation. It fails every time. All other donors seem to work fine. Would you mind explaining how to fix the problem?

Hi Ghardin,
It's difficult to fix the problem when the issue happen with only one donor.
Thanks
Dam

Apperently you were able to fix it for the previous user in this thread, but only in the ticket system. It would be great if you could explain what you did.