500 – Internal Server Error after creating product feed for Google Shopping

Hi,
It was the first time I used your plugin and created a product feed for Google Merchant Centre. While it looked all good from every aspect, it gave an error message “500 – Internal Server Error” when clicking the View button after the feed was generated.
I suspected this was caused by my security plugin so I turned it off. However, the issue still exists and it means it has nothing to do with that plugin.
Would you please take a review and advise what could be the possible reason for the problem.
Thank you and kind regards,
Martin