Magento – Invalid value for Attribute Set column (set does not exists?) in rows: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,

I'm not 100 sure but I think it has something to do with the status or visibility or the product.
In the products grid, when retrieving the collection there are 2 inner joins for selecting the status and visibility. (actually there is a third one, for the name but I doubt this is the problem).
If there are no values for visibility and status the product does not appear in the grid.
To test this, edit any product in the backend, then look in the table catalog_product_entity for a record that does not appear in the grid.
Change the id in the url with the one from the product that does not appear and you should be able to edit it. Set a visibility and status and save. If it appears after that int he grid then this is the problem for sure.

TO solve it, make all your products enabled and visible with this script. You can disable later the ones you don't need.

Crete a file called fix.php in the root of the magento instance with this code

<?php
error_reporting(E_ALL | E_STRICT);
define('MAGENTO_ROOT', getcwd());
$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
require_once $mageFilename;
Mage::app();
$ids = Mage::getModel('catalog/product')->getCollection()->getAllIds();
Mage::getSingleton('catalog/product_action')->updateAttributes(
    $ids,
    array('status'=>1, 'visibility'=>4),
    0
);

When you import data using Magento Import Export Functionality and Migrate from the One Version to Another version please follow the below steps.

Step 1: First Export the Both Version File and Identify What are changes in Headers. Because It will may differ Version to version.

Step 2: Once you identify which Header are Changes or Updated Then Export the Latest data File From Old Version.

Step:3: Open That File in notepad or Noted ++ OR EXCEL And Changes the Header Name as per New Version. Sometimes Boolean Values also changes so also check values and update CVS file.

Step 4: Once all Changes are done. Try to Upload CSV file on Latest Version and Check if you got this error Message or not.

Can not find required columns: email, _website Please fix errors and re-upload file

Stps 5: If you not Found that error then you can import data.

NOTE: Before do any changes on live site please test on environment.