[SOLVED partially] Error 500 after paypal payment in sandbox mode

[visitmontaione]

Hello, I've setup a payment method: Paypal Standard and tested with sandbox.

My website is based on Joomla 4.2.5. and Virtuemart 4.0.7 10744

After all purchase process, and inserted all user/pw of the sandbox I have 2 kind of errors:

1- After the payment, clicking on "back to the vendor website", I get an error 500 (see attachment). Than if click on the back arrow of the browser (Chrome in my case, but the same with Firefox), I see again "back to the vendor website" (see attachment) it goes back to the website correctly.

2- The WEIRD thing is that I continue to receive in loop the same order, once avery 2/3 minutes

Does anyone have the same issue? Maybe a bug?

Thanks for helping.

[visitmontaione]

I've partially solved because it was a problem of my template.

By the way, after the purchasing process, any emails are sent to vendor and customer.

Purchase is not accepted but remain "pending".