TOPIC: Return from successful PayPal goes to 404 error page

I noticed that after a successful PayPal payment for a registration event, the redirect returns to a 404 Error page on the originating website.
How do we resolve this? Thanks.

https://[site]/index.php/en/?option=com_dtregister&controller=payment&task=success&Itemid=

What version of Joomla and DT Register are you running? In testing with the latest of both, PayPal is working just fine.

What is your SEF configuration? Core Joomla only or using a 3rd party component?

Joomla 3.4.8 and DT Register 3.1.6e.

Joomla SEF enabled.
Joomla URL Rewriting enabled.
System - DT Register SSL plugin 1.8 enabled.

Thanks for looking into this.

Are you using sh404SEF by chance? Or another 3rd party SEF extension?

Hi Nathan,
No, not that I can see or know of... not running any 3rd party SEF stuff.

Any update/progress on this issue?
The Joomla site is in a subfolder of the main domain by the way ([www.[domain-name].com/[subfolder]/), if that makes a difference. The redirect (or return from PayPal) used to work OK but after DT Register updates now the return goes to a 404 error.
Thanks.