Old Site Link - http://www.emmaseppala.com/ - Theme - Folioway
Updated Site Link - https://emmaseppala.com - Theme - Pencil designs soledad

Above domain was hosted in amazon aws server previously. We redesigned the site with new theme, updated the domain to https and new wordpress web hosting server. After we activated the plugin with order email and order id your plugin activated in new site. After that we tried to enable the post opt-in form and checked the post details page. But post details page shows empty screen after we enabled the post opt-in form.

1. Can you help me to fix this please ? We got error "Error 500" while preview the created opt-in form.
2. But the same plugin working in old site, can you confirm why we are not able to use the plugin in our new updated site ?
3. What could be the possible issues in this as we just changed the theme to new one and new server for the same site ?
Note: We have updated the new site url in member page also. http://www.wpsubscribers.com/member