Can you provide the full output log from the package attempt? Do you get the same message when trying to package other projects? Is your package configuration set to Development or Shipping? Please let me know what your setup is to help me investigate the issue on my end.
Thank you for letting me know about adding DesktopPlatform. I have reproduced this issue and logged a report for it here Unreal Engine Issues and Bug Tracker (UE-43723) . You can track the report’s status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.
It was brought to my attention that DesktopPlatform is a development module, which is against the EULA to distribute with shipped games. This is why attempting to include it when packaging is causing the package to fail.