Can't change attribute sets via csv import [Magento 2.1.0]

[RG-1]

Steps to reproduce

1. Magento 2.1.0
2. Go to Stores > Attribute: Attribute Sets and create two new sets (e.g. S-1 and S-2)
3. Assign some attributes to sets
4. Create a csv file with products. Value of attribute_set_code should be "S-1"
5. Go to System > Data transfer: Import
6. Import products [Import Behavior: Add/Update]
7. Edit csv file. Change value of attribute_set_code to "S-2"
8. Go to System > Data transfer: Import
9. Import products [Import Behavior: Add/Update]
10. Nothing is changed, so import products one more time, but change Import Behavior to Replace

Expected result

1. Since Magento 2.1.0 it is possible to change attribute sets when editing products. I think that it should be possible on products update via import.

Actual result

1. Attribute Sets are not changed.
2. Imports are successful, without any errors.
3. Only way to change attributes set is to delete products with old set and import products with new set.

Example files

"sku","store_view_code","attribute_set_code","product_type","categories","product_websites","name","weight","product_online","tax_class_name","visibility","price","url_key","display_product_options_in","msrp_display_actual_price_type","country_of_manufacture","qty","out_of_stock_qty","use_config_min_qty","is_qty_decimal","allow_backorders","use_config_backorders","min_cart_qty","use_config_min_sale_qty","max_cart_qty","use_config_max_sale_qty","is_in_stock","notify_on_stock_below","use_config_notify_stock_qty","manage_stock","use_config_manage_stock","use_config_qty_increments","qty_increments","use_config_enable_qty_inc","enable_qty_increments","is_decimal_divided","website_id","deferred_stock_update","use_config_deferred_stock_update"
"Simple1",,"S-1","simple","Default Category/issue",,"Simple 1",1,1,"Taxable Goods","Catalog, Search",10,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1
"Simple2",,"S-1","simple","Default Category/issue",,"Simple 2",1,1,"Taxable Goods","Catalog, Search",20,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1
"Simple3",,"S-1","simple","Default Category/issue",,"Simple 3",1,1,"Taxable Goods","Catalog, Search",30,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1

"sku","store_view_code","attribute_set_code","product_type","categories","product_websites","name","weight","product_online","tax_class_name","visibility","price","url_key","display_product_options_in","msrp_display_actual_price_type","country_of_manufacture","qty","out_of_stock_qty","use_config_min_qty","is_qty_decimal","allow_backorders","use_config_backorders","min_cart_qty","use_config_min_sale_qty","max_cart_qty","use_config_max_sale_qty","is_in_stock","notify_on_stock_below","use_config_notify_stock_qty","manage_stock","use_config_manage_stock","use_config_qty_increments","qty_increments","use_config_enable_qty_inc","enable_qty_increments","is_decimal_divided","website_id","deferred_stock_update","use_config_deferred_stock_update"
"Simple1",,"S-2","simple","Default Category/issue",,"Simple 1",1,1,"Taxable Goods","Catalog, Search",10,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1
"Simple2",,"S-2","simple","Default Category/issue",,"Simple 2",1,1,"Taxable Goods","Catalog, Search",20,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1
"Simple3",,"S-2","simple","Default Category/issue",,"Simple 3",1,1,"Taxable Goods","Catalog, Search",30,,"Block after Info Column","Use config",,5,0,1,0,0,1,1,0,0,1,1,,1,0,1,1,0,1,0,0,1,0,1

[BaDos]

Hi @RG-1

Thank you for reporting.
The internal ticket MAGETWO-58385 was created to resolve this issue.

[isitnikov]

@RG-1 please try such workaround:

diff --git a/vendor/magento/module-catalog-import-export/Model/Import/Product.php b/vendor/magento/module-catalog-import-export/Model/Import/Product.php
index 970b8a1..f6e7961 100644
--- a/vendor/magento/module-catalog-import-export/Model/Import/Product.php
+++ b/vendor/magento/module-catalog-import-export/Model/Import/Product.php
@@ -1296,7 +1296,7 @@ class Product extends \Magento\ImportExport\Model\Import\Entity\AbstractEntity
             $entityTable = $this->_resourceFactory->create()->getEntityTable();
         }
         if ($entityRowsUp) {
-            $this->_connection->insertOnDuplicate($entityTable, $entityRowsUp, ['updated_at']);
+            $this->_connection->insertOnDuplicate($entityTable, $entityRowsUp, ['updated_at', 'attribute_set_id']);
         }
         if ($entityRowsIn) {
             $this->_connection->insertMultiple($entityTable, $entityRowsIn);
@@ -1478,7 +1478,12 @@ class Product extends \Magento\ImportExport\Model\Import\Entity\AbstractEntity
                         'updated_at' => (new \DateTime())->format(DateTime::DATETIME_PHP_FORMAT),
                         $this->getProductEntityLinkField()
                             => $this->_oldSku[$rowSku][$this->getProductEntityLinkField()],
+                        'attribute_set_id' => isset($this->_attrSetNameToId[$rowData['attribute_set_code']])
+                            ? $this->_attrSetNameToId[$rowData['attribute_set_code']]
+                            : $this->_oldSku[$rowSku]['attr_set_id'],
                     ];
+
+                    $rowData[self::COL_ATTR_SET] = $rowData['attribute_set_code'];
                 } else {
                     if (!$productLimit || $productsQty < $productLimit) {
                         $entityRowsIn[$rowSku] = [

[antbates91]

@isakov I've noticed that the following patch will error if a csv is imported without the attribute_set_code column.

Other than that it fixes the issue and you can import changes to Attribute Set Codes without issue.