Check the copy bundle resources in your build phases to see if your Images.xcassets (which is the folder where your AppIcon is located) have been added to it. If not, add it. If you add his prompt "multiple commands product Assets. car", then add this line of code
"install! 'cocoapods',: disable_input_output_paths=>true"
to the podfile and execute pod install, then archive it again and upload.