Is this something related with? 

• https://webmasters.stackexchange.com/a/128680
• https://www.chromium.org/updates/same-site/faq

You are saying your session is 'destroyed'. I think you should investigate if this is truly the case. You need to confirm if your session cookie is still available. If so, could there be a reason that the session is 'removed'? Sessions (and also the session cookie) have a limited lifetime. 

There might also be another reason that the session is 'reset'. You can check that by looking at the identifier in the session cookie. If that changes, something reset the session. This normally only happens when a user logs in/out.

Be aware that session data is not copied from a logged out user to a logged in user. So if you have done something in your session as a logged out user and that user logs in, he/she loses the session data (as a new session is generated on login). If you need logged out user session data transferred to the logged in user, you need to copy this somewhere in your code.

Hi Jeroen,

This is not a login / logout issue. This is exactly how it happens

1. User logs in to elgg website (normal user login)
2. Logged in user clicking on the "Proceed to payment" button (within elgg site)
3. This will submit the form to the payment gateway website, with a hidden callback url parameter (which is a url in elgg website)
4. Once payment is processed / cancelled, payment gateway sends the userback to the callback url (in the same browser); but randomly the users cookie is getting changed and user is now logged out of the system.

This is the exact problem they mentioned in the stackexchange webmaster link. Is this related with the same-site issue?

@Rohit Gupta Thanks for https://tradeguide.in/home - Awesome work!

@Sarath Elgg is not CMS but a framework that has several tools: functions library, classes, services, API.

There is some model/logic of your project based on Elgg (we calls them distributions but Elgg already has starter- project).
The default view of this project can be easily replaced by your owned views.

@Sarath Elgg is not CMS but a framework that has several tools: functions library, classes, services, API.

That exactly what I said. I am using Elgg as a framework only. But my worry is in duplicating all codes. There are many core elements which cannot be easily over-rided by copying the view files to your plugins.. And when you copy these core view files into your theme / plugin, each time when a new elgg version launches you have to cross check the core and may have to adapt to it. 

If using a framework for theming, a big chunk of duplicated core codes can be eliminated and further developments can be easily done using these frameworks.

I think ismayil did some work on elgg and foundation UI framework in past. He understood the real pain in using the duplicated core codes.

@Rohit : I see that you are using boot strap for tradeguid website.

If you and @Rvr looks into the code of your website, you can understand what I meant.

1. You are loading bootstrap UI over Elgg
2. Elgg got its own css and js codes for breadcrumps, navigation, modules, forms, buttons, image_blocks, system_messages, colorbox, popups etc..
3. Css, js for similar functionalities you are again loading through your bootstrap library.
4. Now this results in unnecessary code bloat.

Instead if Elgg is using a popular established UI framework for its core, we can theme additional contents easily.