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
This could be the solution according to Github (Link to Github)
Keep the URL key column blank, and make sure you have added the correct category name with upper and lower case letter.
Make sure the total length of your categories CSV column is shorter than 255 characters. You can check your url_key length too, but I haven't run into issues with my data set on that one.