I feel very happy while I am publishing this post. As a Magento developer. I handle this issue in one of a project. You can resolve Magento product export – Entity is unknown error from admin settings.
Kindly follow these step. I hope it will fix your issue.
Go to the Store > Configuration > General > Web > Session Validation Settings > Use SID on Storefront and set its value to No
1. Login to Magento admin dashboard
2. Click System > Configuration link.
3. The configuration page has left-hand side tabs. Click on “Web” tab under General Tab.
4. Click on “Session Validation Settings”.
5. “Use SID on Frontend” update this setting from “No” to “Yes”.
What is SID?
The SID is a “session ID”. Magento uses this to track a user’s activity within the same Magento installation. Normally, Magento powers one website and one store from one installation (database).
This solution has tested on Magento 1.9.3 version. I hope it will work for old and new versions as well.
