When you have http 500 error while trying to add an image file to your product on vtigerCRM installed in Synology NAS read this.
Go to your Synology settings.
Main Menu -> Web Station -> Script Language Settings -> Select vtigerCRM -> Edit -> Extensions tab -> Enable "exif"
Now it works.
My vtigerCRM version is 7.4 and PHP version is 7.4
You're welcome.
