Here I have attached two csv for configurable and simple product for your demo purpose so you can take reference on how to create it. Please try to import for simple product csv and then configurable one. I had tested it and its working fine.
Simple Product CSV
sku,attribute_set_code,product_type,categories,product_websites,color,additional_attributes,name,description,short_description,weight,product_online,tax_class_name,visibility,price,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,errors
400110821753,Default,simple,Default Category/Women,base,BLACK,"color=BLACK,size=L",Test Product,Test Product,Test Product,4.5,1,None,Not Visible Individually,66.67,100,1,0,0,1,1,1,0,1,1,,1,1,1,1,0,1,0,0,1,0,1,
Configurable Product CSV
sku,store_view_code,attribute_set_code,product_type,categories,product_websites,name,description,short_description,weight,product_online,tax_class_name,visibility,price,special_price,special_price_from_date,special_price_to_date,url_key,meta_title,meta_keywords,meta_description,base_image,base_image_label,small_image,small_image_label,thumbnail_image,thumbnail_image_label,swatch_image,swatch_image_label,created_at,updated_at,new_from_date,new_to_date,display_product_options_in,map_price,msrp_price,map_enabled,gift_message_available,custom_design,custom_design_from,custom_design_to,custom_layout_update,page_layout,product_options_container,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,related_skus,crosssell_skus,upsell_skus,additional_images,additional_image_labels,hide_from_product_page,bundle_price_type,bundle_sku_type,bundle_price_view,bundle_weight_type,bundle_values,configurable_variations,configurable_variation_labels,associated_skus
GC_105-0S2,,Default,configurable,Default Category/Women,base,ConfProd Test,ConfProd Test,ConfProd Test,,1,None,"Catalog, Search",66.67,,,,ConfProd Test,,,,/c/l/classic_fit_1_2.jpg,,/c/l/classic_fit_1_2.jpg,,/c/l/classic_fit_1_2.jpg,,,,,,,,Block after Info Column,,,,,,,,,,,,,0,0,1,0,0,1,1,1,0,1,1,,1,1,1,1,0,1,0,0,1,0,1,,,,/c/l/classic_fit_1_2.jpg,,,,,,,,"sku=400110821753,color=BLACK,size=L","color=Color,size=Size",
Best Answer
I had this and after doing random 1 line imports, I found it was some characters in the descriptions. I had to open the csv in Notepad++ and go Encoding> Convert to UTF-8-BOM then save it as a copy. Went straight on then.