I have website, that is base on PHP but there is a undefined error occur automatic

[highadventure43]

I have Hotel website, naturevilas.com, after updating a PHP version code there is undefined error occur automatic, I don't know why this error occur and I have a big problem because this error can effect my business. I am also going software company in my local area but still I am facing a problem. I don't know how to solve this problem. Error on My Website showing in Font Screen: Bolt Error Back to merchant

website link: naturevilas.com

Home Page

Room Page

Select a Room

CheckOut Page

Error Page

What I have tried:

I have tried, update my PHP Code or back to old version of PHP Code(Backup file) and Connect with my local area software company, but still facing a problem.

Edited August 7, 2021 by requinix
unlinking

[gw1500se]

What is the error? What exactly did you change? When you say you upgraded PHP code do you mean you upgraded PHP itself? If so from what version to what version?

[requinix]

The request to citruspay.com/payu/icpcheckout returns a 400. It does not say why. You'll have to look at the documentation to find out what was wrong with the form data you submitted.

I see a Javascript SDK on GitHub. Are you using it?